TY - JOUR
A1 - Feng, Yiqing
A1 - Kochovski, Zdravko
A1 - Arenz, Christoph
A1 - Lu, Yan
A1 - Kneipp, Janina
T1 - Structure and interaction of ceramide-containing liposomes with gold nanoparticles as characterized by SERS and Cryo-EM
JF - The journal of physical chemistry : C, Nanomaterials and interfaces
N2 - Due to the great potential of surface-enhanced Raman scattering (SERS) as local vibrational probe of lipid-nanostructure interaction in lipid bilayers, it is important to characterize these interactions in detail.
The interpretation of SERS data of lipids in living cells requires an understanding of how the molecules interact with gold nanostructures and how intermolecular interactions influence the proximity and contact between lipids and nanoparticles.
Ceramide, a sphingolipid that acts as important structural component and regulator of biological function, therefore of interest to probing, lacks a phosphocholine head group that is common to many lipids used in liposome models.
SERS spectra of liposomes of a mixture of ceramide, phosphatidic acid, and phosphatidylcholine, as well as of pure ceramide and of the phospholipid mixture are reported.
Distinct groups of SERS spectra represent varied contributions of the choline, sphingosine, and phosphate head groups and the structures of the acyl chains. Spectral bands related to the state of order of the membrane and moreover to the amide function of the sphingosine head groups indicate that the gold nanoparticles interact with molecules involved in different intermolecular relations.
While cryogenic electron microscopy shows the formation of bilayer liposomes in all preparations, pure ceramide was found to also form supramolecular, concentric stacked and densely packed lamellar, nonliposomal structures. That the formation of such supramolecular assemblies supports the intermolecular interactions of ceramide is indicated by the SERS data.
The unique spectral features that are assigned to the ceramide-containing lipid model systems here enable an identification of these molecules in biological systems and allow us to obtain information on their structure and interaction by SERS.
Y1 - 2022
U6 - https://doi.org/10.1021/acs.jpcc.2c01930
SN - 1932-7447
SN - 1932-7455
VL - 126
IS - 31
SP - 13237
EP - 13246
PB - American Chemical Society
CY - Washington, DC
ER -
TY - JOUR
A1 - Tritschler, Ulrich
A1 - Delgado López, José Manuel
A1 - Umbach, Tobias R.
A1 - Van Driessche, Alexander E. S.
A1 - Schlaad, Helmut
A1 - Cölfen, Helmut
A1 - Kellermeier, Matthias
T1 - Oriented attachment and aggregation as a viable pathway to self-assembled organic/inorganic hybrid materials
JF - CrystEngComm
N2 - Organic-inorganic composite materials with tailored properties can be designed in the lab through bioinspired approaches.
In this context, we exploited the particle-based crystallisation process of calcium sulfate, a technologically important mineral, to hybridise inorganic and organic matter.
We identified and synthesised an organic polymer showing strong affinity to bind to the surfaces of mineral precursors as well as intrinsic tendency to self-organise. Subsequently, polymer-coated building units were allowed to self-assemble via oriented attachment, aggregation and phase transformation, which produced ordered superstructures where the organic polymer is intercalated between the subunits and surrounds the hybrid core as a shell.
This specific architecture across multiple length scales leads to unique mechanical properties, comparable to those of natural biominerals.
Thus, our results devise a straightforward pathway to prepare organic-inorganic hybrid structures via bottom-up self-assembly processes innate to the crystallisation of the inorganic phase.
This approach can likely be transferred to other inorganic minerals, affording next-generation materials for applications in the construction sector, biomedicine and beyond.
Y1 - 2022
U6 - https://doi.org/10.1039/d2ce00447j
SN - 1466-8033
VL - 24
IS - 36
SP - 6320
EP - 6329
PB - Royal Society of Chemistry
CY - London
ER -
TY - JOUR
A1 - Cortez, Nicole
A1 - Marin, Victor
A1 - Jimenez, Veronica A.
A1 - Silva, Victor
A1 - Leyton, Oscar
A1 - Cabrera-Pardo, Jaime R.
A1 - Schmidt, Bernd
A1 - Heydenreich, Matthias
A1 - Burgos, Viviana
A1 - Duran, Paola
A1 - Paz, Cristian
T1 - Drimane sesquiterpene alcohols with activity against Candida yeast obtained by biotransformation with Cladosporium antarcticum
JF - International journal of molecular sciences
N2 - Fungal biotransformation is an attractive synthetic strategy to produce highly specific compounds with chemical functionality in regions of the carbon skeleton that are not easily activated by conventional organic chemistry methods.
In this work, Cladosporium antarcticum isolated from sediments of Glacier Collins in Antarctica was used to obtain novel drimane sesquiterpenoids alcohols with activity against Candida yeast from drimendiol and epidrimendiol. These compounds were produced by the high-yield reduction of polygodial and isotadeonal with NaBH4 in methanol.
Cladosporium antarcticum produced two major products from drimendiol, identified as 9 alpha-hydroxydrimendiol (1, 41.4 mg, 19.4% yield) and 3 beta-hydroxydrimendiol (2, 74.8 mg, 35% yield), whereas the biotransformation of epidrimendiol yielded only one product, 9 beta-hydroxyepidrimendiol (3, 86.6 mg, 41.6% yield).
The products were purified by column chromatography and their structure elucidated by NMR and MS. The antifungal activity of compounds 1-3 was analyzed against Candida albicans, C. krusei and C. parapsilosis, showing that compound 2 has a MIC lower than 15 mu g/mL against the three-pathogenic yeast.
In silico studies suggest that a possible mechanism of action for the novel compounds is the inhibition of the enzyme lanosterol 14 alpha-demethylase, affecting the ergosterol synthesis.
KW - Drimys winteri
KW - Cladosporium antarcticum
KW - drimendiol
KW - epidrimendiol
KW - biotransformation
KW - Candida yeast
KW - lanosterol 14 alpha-demethylase
KW - biocontrol
Y1 - 2022
U6 - https://doi.org/10.3390/ijms232112995
SN - 1422-0067
VL - 23
IS - 21
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Marin, Victor
A1 - Bart, Bryan
A1 - Cortez, Nicole
A1 - Jiménez, Verónica A.
A1 - Silva, Victor
A1 - Leyton, Oscar
A1 - Cabrera-Pardo, Jaime R.
A1 - Schmidt, Bernd
A1 - Heydenreich, Matthias
A1 - Burgos, Viviana
A1 - Paz, Cristian
T1 - Drimane sesquiterpene aldehydes control Candida yeast isolated from candidemia in Chilean patients
JF - International journal of molecular sciences
N2 - Drimys winteri J.R. (Winteraceae) produce drimane sesquiterpenoids with activity against Candida yeast.
In this work, drimenol, polygodial (1), isotadeonal (2), and a new drimane alpha,beta-unsaturated 1,4-dialdehyde, named winterdial (4), were purified from barks of D. winteri. The oxidation of drimenol produced the monoaldehyde drimenal (3).
These four aldehyde sesquiterpenoids were evaluated against six Candida species isolated from candidemia patients in Chilean hospitals.
Results showed that 1 displays fungistatic activity against all yeasts (3.75 to 15.0 mu g/mL), but irritant effects on eyes and skin, whereas its non-pungent epimer 2 has fungistatic and fungicide activities at 1.9 and 15.0 mu g/mL, respectively.
On the other hand, compounds 3 and 4 were less active.
Molecular dynamics simulations suggested that compounds 1-4 are capable of binding to the catalytic pocket of lanosterol 14-alpha demethylase with similar binding free energies, thus suggesting a potential mechanism of action through the inhibition of ergosterol synthesis. According to our findings, compound 2 appears as a valuable molecular scaffold to pursue the future development of more potent drugs against candidiasis with fewer side effects than polygodial.
These outcomes are significant to broaden the alternatives to treat fungal infections with increasing prevalence worldwide using natural compounds as a primary source for active compounds.
KW - drimane sesquiterpenoids
KW - Drimys winteri
KW - isotadeonal
KW - winterdial
KW - Candida yeast
KW - lanosterol 14-α-demethylase
KW - molecular dynamics
Y1 - 2022
U6 - https://doi.org/10.3390/ijms231911753
SN - 1422-0067
VL - 23
IS - 19
PB - Molecular Diversity Preservation International
CY - Basel
ER -
TY - JOUR
A1 - Schürmann, Robin
A1 - Dutta, Anushree
A1 - Ebel, Kenny
A1 - Tapio, Kosti
A1 - Milosavljevic, Aleksander R.
A1 - Bald, Ilko
T1 - Plasmonic reactivity of halogen thiophenols on gold nanoparticles studied by SERS and XPS
JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2 - Localized surface plasmon resonances on noble metal nanoparticles (NPs) can efficiently drive reactions of adsorbed ligand molecules and provide versatile opportunities in chemical synthesis. The driving forces of these reactions are typically elevated temperatures, hot charge carriers, or enhanced electric fields.
In the present work, dehalogenation of halogenated thiophenols on the surface of AuNPs has been studied by surface enhanced Raman scattering (SERS) as a function of the photon energy to track the kinetics and identify reaction products.
Reaction rates are found to be surprisingly similar for different halothiophenols studied here, although the bond dissociation energies of the C-X bonds differ significantly. Complementary information about the electronic properties at the AuNP surface, namely, work-function and valence band states, has been determined by x-ray photoelectron spectroscopy of isolated AuNPs in the gas-phase.
In this way, it is revealed how the electronic properties are altered by the adsorption of the ligand molecules, and we conclude that the reaction rates are mainly determined by the plasmonic properties of the AuNPs. SERS spectra reveal differences in the reaction product formation for different halogen species, and, on this basis, the possible reaction mechanisms are discussed to approach an understanding of opportunities and limitations in the design of catalytical systems with plasmonic NPs.
Y1 - 2022
U6 - https://doi.org/10.1063/5.0098110
SN - 0021-9606
SN - 1089-7690
VL - 157
IS - 8
PB - American Institute of Physics
CY - Melville, NY
ER -
TY - JOUR
A1 - Braune, S.
A1 - Baeckemo, J.
A1 - Lau, S.
A1 - Heuchel, M.
A1 - Kratz, K.
A1 - Jung, F.
A1 - Reinthaler, M.
A1 - Lendlein, Andreas
T1 - The influence of different rewetting procedures on the thrombogenicity of nanoporous poly(ether imide) microparticles
JF - Clinical hemorheology and microcirculation : blood flow and vessels
N2 - Nanoporous microparticles prepared from poly(ether imide) (PEI) are discussed as candidate adsorber materials for the removal of uremic toxins during apheresis. Polymers exhibiting such porosity can induce the formation of micro-gas/air pockets when exposed to fluids. Such air presenting material surfaces are reported to induce platelet activation and thrombus formation. Physical or chemical treatments prior to implantation are discussed to reduce the formation of such gas nuclei. Here, we report about the influence of different rewetting procedures - as chemical treatments with solvents on the thrombogenicity of hydrophobic PEI microparticles and PEI microparticles hydrophilized by covalent attachment of poly(vinyl pyrrolidone) (PVP) of two different chain lengths.
Autoclaved dry PEI particles of all types with a diameter range of 200 - 250 mu m and a porosity of about 84%+/- 2% were either rewetted directly with phosphate buffered saline (24 h) or after immersion in an ethanol-series. Thrombogenicity of the particles was studied in vitro upon contact with human sodium citrated whole blood for 60 min at 5 rpm vertical rotation. Numbers of non-adherent platelets were quantified, and adhesion of blood cells was qualitatively analyzed by bright field microscopy. Platelet activation (percentage of CD62P positive platelets and amounts of soluble P-Selectin) and platelet function (PFA100 closure times) were analysed.
Retention of blood platelets on the particles was similar for all particle types and both rewetting procedures. Non-adherent platelets were less activated after contact with ethanol-treated particles of all types compared to those rewetted with phosphate buffered saline as assessed by a reduced number of CD62P-positive platelets and reduced amounts of secreted P-Selectin (P < 0.05 each). Interestingly, the hydrophilic surfaces significantly increased the number of activated platelets compared to hydrophobic PEI regardless of the rewetting agent. This suggests that, apart from wettability, other material properties might be more important to regulate platelet activation. PFA100 closure times were reduced and within the reference ranges in the ethanol group, however, significantly increased in the saline group. No substantial difference was detected between the tested surface modifications. In summary, rewetting with ethanol resulted in a reduced thrombogenicity of all studied microparticles regardless of their wettability, most likely resulting from the evacuation of air from the nanoporous particles.
KW - biomaterial
KW - polymer
KW - microparticle
KW - thrombogenicity
KW - hemocompatibility
KW - dynamic in-vitro test
KW - rewetting
Y1 - 2021
U6 - https://doi.org/10.3233/CH-201029
SN - 1386-0291
SN - 1875-8622
VL - 77
IS - 4
SP - 367
EP - 380
PB - IOS Press
CY - Amsterdam
ER -
TY - JOUR
A1 - Farrokhzadeh, Abdolkarim
A1 - Modarresi-Alam, Ali Reza
A1 - Akher, Farideh Badichi
A1 - Kleinpeter, Erich
A1 - Kelling, Alexandra
A1 - Schilde, Uwe
T1 - Investigation of the unusually high rotational energy barrier about the C-N bond in 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides
BT - insights from dynamic H-1-NMR and DFT calculations
JF - Journal of molecular structure
N2 - In this study, the synthesis of new 5 (2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides (X = H and Cl) is reported coupled with the investigation of their dynamic H-1-NMR via rotation about C-N bonds in the moiety of urea group [a; CO-NMe2] in DMSO solvent (298-373 K). Accordingly, activation free energies of 17.32 and 17.50 kcal mol(-1) were obtained for X = H and Cl respectively, with respect to the conformational isomerization about the Me2N-C=O bond (a rotation). Moreover, a and b [b; 2-tetrazolyl-CO rotations] barrier to rotations in 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides were also calculated by B3LYP/6-311++G** procedure. The optimized geometry parameters are well consistent with the X-ray data. Computed rotational energy barriers (X = Cl) for a and b were estimated to be 17.52 and 2.53 kcal mol(-1), respectively, the former in agreement with the dynamic NMR results. X-ray structures verify that just 2-acylated tetrazoles are formed in the case of 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides. A planar trigonal orientation of the Me2N group was proven by X-ray data, which is coplanar to the carbonyl group, coupled with partial double bond C-N character. This also illustrates the syn-periplanar position of the tetrazolyl ring with C=O group. In solution, the planes containing tetrazolyl ring and the carbonyl bond are almost perpendicular to each other (because of steric effects as confirmed by calculations) while the planes containing carbonyl bond and Me2N group are coplanar. This phenomenon is in contrast with similar urea derivatives and explains the reason for the unusually high rotational energy barrier of these compounds. (C) 2020 Elsevier B.V. All rights reserved.
KW - carbamoyl tetrazoles
KW - barrier to rotation about C-N bond
KW - dynamic
KW - H-1-NMR
KW - quantum mechanical calculations
KW - X-ray structures
Y1 - 2020
U6 - https://doi.org/10.1016/j.molstruc.2020.129363
SN - 0022-2860
SN - 1872-8014
VL - 1226
IS - Part B
PB - Elsevier
CY - New York, NY
ER -
TY - JOUR
A1 - Stojanović, Ivan
A1 - Židov, Bruno
A1 - Travkova, Oksana
A1 - Grigoriev, Dmitry
T1 - Enhanced protective performance of waterborne, microcontainers-doped coatings in harsh environments
JF - Progress in organic coatings : an international journal
N2 - In this study, the corrosion inhibitors Zinc oleate and 8-Hydroxyquinoline were successfully encapsulated using an interfacial polyaddition method. As such they were dispersed at different concentrations within the waterborne coating matrix. The resulting composite coatings were applied to the low carbon steel substrates. Successful synthesis and morphological characteristics of microcontainers loaded with inhibitors were confirmed using various characterization techniques. Scanning electron microscopy, dynamic light scattering, and thermogravimetric measurements are techniques used to define the surface, dimensional, and dispersive characteristics of containers, and the share of encapsulated inhibitors. The release study defined the discharge kinetics of the corrosion inhibitor from the microcontainers dispersed freely in an aqueous medium. Electrochemical impedance spectroscopy was used to determine the anticorrosive performance of the samples continuously exposed to various corrosive environments of salt and humidity chambers and NaCl solution. Special emphasis was placed on adhesion testing and visual observations during the exposure period. Significant improvements have been noted in terms of corrosion resistance, which, however, depend on the type of inhibitor used, the concentration of the containers embedded in the coating matrix and on the characteristics of the corrosive environment.
KW - Self-protecting coatings
KW - Interfacial polyaddition
KW - Inhibitor loaded
KW - microcontainers
KW - Corrosion inhibitors
Y1 - 2021
U6 - https://doi.org/10.1016/j.porgcoat.2021.106273
SN - 0300-9440
SN - 1873-331X
VL - 157
PB - Elsevier Science
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Gahlaut, Shashank K.
A1 - Pathak, Anisha
A1 - Gupta, Banshi D.
T1 - Recent advances in silver nanostructured substrates for plasmonic sensors
JF - Biosensors : open access journal
N2 - Noble metal nanostructures are known to confine photon energies to their dimensions with resonant oscillations of their conduction electrons, leading to the ultrahigh enhancement of electromagnetic fields in numerous spectroscopic methods.
Of all the possible plasmonic nanomaterials, silver offers the most intriguing properties, such as best field enhancements and tunable resonances in visible-to-near infrared regions.
This review highlights the recent developments in silver nanostructured substrates for plasmonic sensing with the main emphasis on surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS) over the past decade.
The main focus is on the synthesis of silver nanostructured substrates via physical vapor deposition and chemical synthesis routes and their applications in each sensing regime.
A comprehensive review of recent literature on various possible silver nanostructures prepared through these methodologies is discussed and critically reviewed for various planar and optical fiber-based substrates.
KW - silver
KW - plasmonics
KW - sensors
KW - surface-enhanced Raman spectroscopy
KW - surface-enhanced fluorescence
KW - surface-enhanced infrared spectroscopy
Y1 - 2022
U6 - https://doi.org/10.3390/bios12090713
SN - 2079-6374
VL - 12
IS - 9
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Diehn, Sabrina Maria
A1 - Schlaad, Helmut
A1 - Kneipp, Janina
T1 - Multivariate imaging for fast evaluation of in situ dark field microscopy hyperspectral data
JF - Molecules : a journal of synthetic chemistry and natural product chemistry
N2 - Dark field scattering microscopy can create large hyperspectral data sets that contain a wealth of information on the properties and the molecular environment of noble metal nanoparticles.
For a quick screening of samples of microscopic dimensions that contain many different types of plasmonic nanostructures, we propose a multivariate analysis of data sets of thousands to several hundreds of thousands of scattering spectra.
By using non-negative matrix factorization for decomposing the spectra, components are identified that represent individual plasmon resonances and relative contributions of these resonances to particular microscopic focal volumes in the mapping data sets. Using data from silver and gold nanoparticles in the presence of different molecules, including gold nanoparticle-protein agglomerates or silver nanoparticles forming aggregates in the presence of acrylamide, plasmonic properties are observed that differ from those of the original nanoparticles.
For the case of acrylamide, we show that the plasmon resonances of the silver nanoparticles are ideally suited to support surface enhanced Raman scattering (SERS) and the two-photon excited process of surface enhanced hyper Raman scattering (SEHRS). Both vibrational tools give complementary information on the in situ formed polyacrylamide and the molecular composition at the nanoparticle surface.
KW - localized surface plasmon resonances
KW - gold nanoparticles
KW - silver nanoparticles
KW - dark field microscopy
KW - acrylamide
KW - hyperspectral imaging
KW - non-negative matrix factorization
KW - surface-enhanced Raman scattering (SERS)
KW - surface-enhanced hyper Raman scattering (SEHRS)
Y1 - 2022
U6 - https://doi.org/10.3390/molecules27165146
SN - 1420-3049
VL - 27
IS - 16
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Tarazona, Natalia A.
A1 - Wei, Ren
A1 - Brott, Stefan
A1 - Pfaff, Lara
A1 - Bornscheuer, Uwe T.
A1 - Lendlein, Andreas
A1 - Machatschek, Rainhard
T1 - Rapid depolymerization of poly(ethylene terephthalate) thin films by a dual-enzyme system and its impact on material properties
JF - Chem Catalysis
N2 - Enzymatic hydrolysis holds great promise for plastic waste recycling and upcycling.
The interfacial catalysis mode, and the variability of polymer specimen properties under different degradation conditions, add to the complexity and difficulty of understanding polymer cleavage and engineering better biocatalysts.
We present a systemic approach to studying the enzyme-catalyzed surface erosion of poly(ethylene terephthalate) (PET) while monitoring/controlling operating conditions in real time with simultaneous detection of mass loss and changes in viscoelastic behavior.
PET nanofilms placed on water showed a porous morphology and a thicknessdependent glass transition temperature (T-g) between 40 degrees C and 44 degrees C, which is >20 degrees C lower than the T-g of bulk amorphous PET.
Hydrolysis by a dual-enzyme system containing thermostabilized variants of Ideonella sakaiensis PETase and MHETase resulted in a maximum depolymerization of 70% in 1 h at 50 degrees C.
We demonstrate that increased accessible surface area, amorphization, and T-g reduction speed up PET degradation while simultaneously lowering the threshold for degradation-induced crystallization.
Y1 - 2022
U6 - https://doi.org/10.1016/j.checat.2022.11.004
SN - 2667-1093
SN - 2667-1107
VL - 2
IS - 12
SP - 3573
EP - 3589
PB - Cell Press
CY - Cambridge
ER -
TY - JOUR
A1 - Rothe, Martin
A1 - Zhao, Yuhang
A1 - Halim, Henry
A1 - Lu, Yan
A1 - Benson, Oliver
T1 - Spatial mapping of bleaching in a metal-organic plasmon converter
JF - Optics continuum
N2 - Hybrid nanophotonic elements, fabricated by organic and inorganic materials, are going to be key components of modern devices.
Coupled systems of photoemitters with a plasmonic waveguide serve the demand for nanoscopic frequency converters.
However, processes like the degradation of the photoemitters via photobleaching occur and need to be monitored and controlled, to realize future successful devices.
We introduce a hybrid perylene-diimide / silver nanowire as plasmon frequency converter. A versatile method is presented to monitor and analyze the bleaching process. It is based on a time series of photoluminescence images, during the operation of a single converter.
An analytical model is applied on the data and unveils that the photobleaching rate is constant and independent of the operation of the plasmon converter.
Y1 - 2022
U6 - https://doi.org/10.1364/OPTCON.454911
SN - 2770-0208
VL - 1
IS - 8
SP - 1730
EP - 1740
PB - Optica Publishing Group
CY - Washington
ER -
TY - JOUR
A1 - Chemura, Sitshengisiwe
A1 - Schrumpf, Tim
A1 - Günter, Christina
A1 - Kumke, Michael Uwe
T1 - Ceria nanomaterials containing Ytterbium
BT - Low and high concentration – luminescence analyzed in the near infrared region
JF - RSC Advances : an international journal to further the chemical sciences
N2 - Lanthanide based ceria nanomaterials are important practical materials due to the redox properties that are useful in the avenues pertaining to technology and life sciences. Sub 10 nm spherical and highly monodisperse Ce1−xYbxO2−y (0.04 ≤ x ≤ 0.22) nanoparticles were synthesized by thermal decomposition, annealed separately at 773 K and 1273 K for 2 hours and characterized. Elemental mapping for Yb3+ doped ceria nanoparticles shows homogeneous distribution of Yb3+ atoms in the ceria with low Yb3+ content annealed at 773 K and 1273 K for 2 hours. However, clusters are observed for 773 K annealed ceria samples with high concentration of Yb3+. These clusters are not detected in 1273 K annealed nanomaterials. Introducing small amounts of Yb3+ ions into the ceria lattice as spectroscopic probes can provide detailed information about the atomic structure and local environments allowing the monitoring of small structural changes, such as clustering. The emission spectra observed at room temperature and at 4 K have a manifold of bands that corresponds to the 2F5/2 → 2F7/2 transition of Yb3+ ions. Some small shifts are observed in the Stark splitting pattern depending on the sample and the annealing conditions. The deconvolution by PARAFAC analysis yielded luminescence decay kinetics as well as the associated luminescence spectra of three species for each of the low Yb3+ doped ceria samples annealed at 773 K and one species for the 1273 K annealed samples. However, the ceria samples with high concentration of Yb3+ annealed at the two temperatures showed only one species with lower decay times as compared to the low Yb3+ doped ceria samples.
Y1 - 2023
U6 - https://doi.org/10.1039/D3RA06868D
SN - 2046-2069
VL - 13
IS - 50
SP - 35445
EP - 35456
PB - RSC Publishing
CY - London
ER -
TY - JOUR
A1 - Lehnen, Anne-Catherine
A1 - Kurki, Jan A. M.
A1 - Hartlieb, Matthias
T1 - The difference between photo-iniferter and conventional RAFT polymerization
BT - high livingness enables the straightforward synthesis of multiblock copolymers
JF - Polymer Chemistry
N2 - Photo-iniferter (PI)-RAFT polymerization, the direct activation of chain transfer agents via light, is a fascinating polymerization technique, as it overcomes some restriction of conventional RAFT polymerization.
As such, we elucidated the role of reversible deactivation in this context using a monomer-CTA pair with low chain transfer capabilities.
Tests with varying targeted degrees of polymerization (DP) or monomer concentrations revealed no significant improvement of polymerization control using the PI-process. Control can however be achieved via slow monomer addition, increasing the number of activation/deactivation events per monomer addition.
More importantly, the livingness of the polymerization was found to be extraordinarily high, enabling the straightforward and rapid synthesis of multiblock copolymers with up to 20 blocks and a high number of repeating units per block (DP = 25-100) maintaining an overall excellent definition (M-n = 90 300 g mol(-1), D = 1.29).
This study highlights the enormous potential of PI-RAFT polymerization for the synthesis of polymeric materials.
Y1 - 2022
U6 - https://doi.org/10.1039/d1py01530c
SN - 1759-9954
SN - 1759-9962
VL - 13
IS - 11
SP - 1537
EP - 1546
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Hermanns, Jolanda
A1 - Kunold, Helen
T1 - Mechanism comics as a task in a written exam in organic chemistry for pre-service chemistry teachers
JF - Chemistry teacher international : best practices in chemistry education
N2 - In this paper, we describe and evaluate a study on the use of mechanism comics for writing solutions to a task in a written exam for the course "Organic Chemistry I for Pre-Service Chemistry Teachers."
The students had to design a reaction mechanism for a reaction that was unknown to them and write captions explaining every step of their reaction mechanism.
The students' work was evaluated using the method of qualitative content analysis in four rounds by both authors. The majority of the captions were coded as "descriptive" and only a minority as "causal."
This means that the students mostly described "what" happened, but seldom "why" this happened. Implicit electron movement was also described more often than explicit electron movement. The majority of the captions were technically correct. In summary, the students were capable of designing and describing a reaction mechanism for a previously unknown reaction.
The quality of their reasoning could be improved, however. In the new course, the quality of students' mechanistic reasoning and then especially their explanations of "why" mechanistic steps occur will be given much clearer emphasis.
KW - concepts
KW - mechanistic reasoning
KW - organic chemistry
KW - pre-service chemistry teachers
KW - writing-to-learn
Y1 - 2022
U6 - https://doi.org/10.1515/cti-2021-0035
SN - 2569-3263
VL - 4
IS - 3
SP - 259
EP - 269
PB - De Gruyter
CY - Berlin
ER -
TY - JOUR
A1 - Titov, Evgenii
T1 - Effect of conformational disorder on exciton states of an azobenzene aggregate
JF - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2 - Azobenzene is a prototypical molecular photoswitch, widely used to trigger a variety of transformations at different length scales.
In systems like self-assembled monolayers or micelles, azobenzene chromophores may interact with each other, which gives rise to the emergence of exciton states.
Here, using first-principles calculations, we investigate how conformational disorder (induced, e.g., by thermal fluctuations) affects localization of these states, on an example of an H-type azobenzene tetramer.
We find that conformational disorder leads to (partial) exciton localization on a single-geometry level, whereas ensemble-averaging results in a delocalized picture. The pi pi* and n pi* excitons at high and low temperatures are discussed.
Y1 - 2022
U6 - https://doi.org/10.1039/d2cp02774g
SN - 1463-9076
SN - 1463-9084
VL - 24
IS - 39
SP - 24002
EP - 24006
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Sand, Patrick
A1 - Schmidt, Bernd
T1 - Orthogonal arylation of a diene-sulfonamide using cationic transition metal catalysts
JF - European journal of organic chemistry
N2 - The regioselectivity of two mechanistically distinct alkenylation reactions catalyzed by in situ-formed cationic transition metal complexes was studied using
N-allyl-N-phenylethenesulfonamide as a model compound.
Orthogonal selectivity was observed for the Ru-catalyzed C-H-activating alkenylation with acetanilides, which occurs preferentially at the electron deficient double bond, and for a Pd-catalyzed Heck-type coupling with arene diazonium salts, which occurs preferentially at the more electron rich double bond of the N-allyl substituent.
KW - arenes
KW - C-H activation
KW - palladium
KW - ruthenium
KW - sulfonamides
Y1 - 2022
U6 - https://doi.org/10.1002/ejoc.202201336
SN - 1434-193X
SN - 1099-0690
VL - 2022
IS - 47
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Prüfert, Christian
A1 - Beitz, Toralf
A1 - Reich, Olaf
A1 - Löhmannsröben, Hans-Gerd
T1 - Inline process analysis of copper-bearing aerosols using laser-induced breakdown spectroscopy, laser-induced incandescence and optical imaging
JF - Spectrochimica acta, Part B, Atomic spectroscopy
N2 - The quantification and identification of aerosols in industry plays a key role in process monitoring and control and lays the foundation for process automation aspired by the industry 4.0 initiative.
However, measuring particulate matter's mass and number concentrations in harsh environments poses great analytical constraints.
The presented approach comprises a comprehensive set of light-and imaging-based techniques, all contactless, in-line, and real-time. It includes, but is not limited to, stroboscopic imaging, laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII). Stroboscopic imaging confirmed the particles sphericity and was used to measure the particle number density. A phase-selective LIBS setup with low fluence and 500 Hz repetition rate was used to classify each particle with a single-pulse and in real time. Simultaneously, the created plasma was captured by CCD imaging to determine the detection volume and hit rate of the LIBS setup.
Both data sets combined were converted to a particle number density, which was consistent with the particle number density of the stroboscopic measurements. Furthermore, using a photodiode and microphone in parallel to the LIBS setup allowed for the photoacoustic normalization of the spectral line intensity at the laser repetition rate of 500 Hz.
This was done as a partial photoacoustic normalization method with the cut-off based on the coefficient of variation (CV), reducing it by 25%. Aside from that photodiode and microphone were proven to be valuable event counting with the advantage of the less spatially constricted. A second laser setup was used for laser -induced incandescence (LII) making it possible to classify the particles based on their incandescence tendency. Given its larger probing volume, LII could be employed at very low particle number densities.
With respect to the current literature, this is the first approach of using LII as an in-line, real-time analytical technique for the compositional classification of metal-bearing aerosols.
KW - LIBS
KW - LII
KW - aerosol. photoacoustics
KW - stroboscopic imaging
KW - minerals
Y1 - 2022
U6 - https://doi.org/10.1016/j.sab.2022.106527
SN - 0584-8547
SN - 1873-3565
VL - 197
PB - Elsevier
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Wessig, Pablo
A1 - Badetko, Dominik
A1 - Koebe, Michael
T1 - Triplet sensitized Photo-Dehydro-Diels-Alder reaction
JF - ChemistrySelect
N2 - We report on the triplet sensitization of the intramolecular Photo-Dehydro-Diels-Alder (PDDA) reaction of two diaryl suberates bearing methyl propiolate chromophors. Compared with the non-sensitized irradiation, considerably increased yields could be observed.
Moreover, it is possible to use the more efficient UVA lamps instead of UVB lamps.
Among three investigated sensitizers (xanthone, benzophenone, thioxanthone) xanthone gave the best results.
KW - light sources
KW - photochemistry
KW - photodehydro-Diels-Alder reaction
KW - triplet sensitization
Y1 - 2022
U6 - https://doi.org/10.1002/slct.202202648
SN - 2365-6549
VL - 7
IS - 38
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Ebel, Kenny
A1 - Bald, Ilko
T1 - Low-energy (5-20 eV) electron-induced single and double strand breaks in well-defined DNA sequences
JF - Journal of physical chemistry letters
N2 - Ionizing radiation is used in cancer radiation therapy to effectively damage the DNA of tumors. The main damage is due to generation of highly reactive secondary species such as low-energy electrons (LEEs). The accurate quantification of DNA radiation damage of well-defined DNA target sequences in terms of absolute cross sections for LEE-induced DNA strand breaks is possible by the DNA origami technique; however, to date, it is possible only for DNA single strands. In the present work DNA double strand breaks in the DNA sequence 5 '-d(CAC)4/5 ' d(GTG)4 are compared with DNA single strand breaks in the oligonucleotides 5 '-d(CAC)4 and 5 '-d(GTG)4 upon irradiation with LEEs in the energy range from 5 to 20 eV. A maximum of strand break cross section was found around 7 and 10 eV independent of the DNA sequence, indicating that dissociative electron attachment is the underlying mechanism of strand breakage and confirming previous studies using plasmid DNA.
Y1 - 2022
U6 - https://doi.org/10.1021/acs.jpclett.2c00684
SN - 1948-7185
VL - 13
IS - 22
SP - 4871
EP - 4876
PB - American Chemical Society
CY - Washington, DC
ER -
TY - CHAP
A1 - Wang, Zhenyu
A1 - Breternitz, Joachim
A1 - Schorr, Susan
T1 - Cation disorder in zinc-group IV- nitride and oxide nitride semiconductor materials revealed through neutron diffraction
T2 - Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances
KW - nitride materials
KW - semiconductors
KW - structure-property relationships
Y1 - 2021
U6 - https://doi.org/10.1107/S0108767321086256
SN - 2053-2733
VL - 77
IS - Suppl.
SP - C1077
EP - C1077
PB - Blackwell
CY - Oxford [u.a.]
ER -
TY - JOUR
A1 - Erler, Alexander
A1 - Riebe, Daniel
A1 - Beitz, Toralf
A1 - Löhmannsröben, Hans-Gerd
A1 - Leenen, Mathias
A1 - Pätzold, Stefan
A1 - Ostermann, Markus
A1 - Wójcik, Michał
T1 - Mobile laser-induced breakdown spectroscopy for future application in precision agriculture
BT - a case study
JF - Sensors
N2 - In precision agriculture, the estimation of soil parameters via sensors and the creation of nutrient maps are a prerequisite for farmers to take targeted measures such as spatially resolved fertilization. In this work, 68 soil samples uniformly distributed over a field near Bonn are investigated using laser-induced breakdown spectroscopy (LIBS). These investigations include the determination of the total contents of macro- and micronutrients as well as further soil parameters such as soil pH, soil organic matter (SOM) content, and soil texture. The applied LIBS instruments are a handheld and a platform spectrometer, which potentially allows for the single-point measurement and scanning of whole fields, respectively. Their results are compared with a high-resolution lab spectrometer. The prediction of soil parameters was based on multivariate methods. Different feature selection methods and regression methods like PLS, PCR, SVM, Lasso, and Gaussian processes were tested and compared. While good predictions were obtained for Ca, Mg, P, Mn, Cu, and silt content, excellent predictions were obtained for K, Fe, and clay content. The comparison of the three different spectrometers showed that although the lab spectrometer gives the best results, measurements with both field spectrometers also yield good results. This allows for a method transfer to the in-field measurements.
KW - LIBS
KW - precision agriculture
KW - soil
KW - multivariate methods
KW - feature selection
Y1 - 2023
U6 - https://doi.org/10.3390/s23167178
SN - 1424-8220
VL - 23
IS - 16
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Adesina, Morenike O.
A1 - Block, Inga
A1 - Günter, Christina
A1 - Unuabonah, Emmanuel Iyayi
A1 - Taubert, Andreas
T1 - Efficient Removal of Tetracycline and Bisphenol A from Water with a New Hybrid Clay/TiO₂ Composite
JF - ACS Omega
N2 - New TiO₂ hybrid composites were prepared fromkaolinclay, predried and carbonized biomass, and titanium tetraisopropoxideand explored for tetracycline (TET) and bisphenol A (BPA) removalfrom water. Overall, the removal rate is 84% for TET and 51% for BPA.The maximum adsorption capacities (q (m))are 30 and 23 mg/g for TET and BPA, respectively. These capacitiesare far greater than those obtained for unmodified TiO2. Increasing the ionic strength of the solution does not change theadsorption capacity of the adsorbent. pH changes only slightly changeBPA adsorption, while a pH > 7 significantly reduces the adsorptionof TET on the material. The Brouers-Sotolongo fractal modelbest describes the kinetic data for both TET and BPA adsorption, predictingthat the adsorption process occurs via a complex mechanism involvingvarious forces of attraction. Temkin and Freundlich isotherms, whichbest fit the equilibrium adsorption data for TET and BPA, respectively,suggest that adsorption sites are heterogeneous in nature. Overall,the composite materials are much more effective for TET removal fromaqueous solution than for BPA. This phenomenon is assigned to a differencein the TET/adsorbent interactions vs the BPA/adsorbent interactions:the decisive factor appears to be favorable electrostatic interactionsfor TET yielding a more effective TET removal.
Y1 - 2023
U6 - https://doi.org/10.1021/acsomega.3c00184
SN - 2470-1343
VL - 8
IS - 24
SP - 21594
EP - 21604
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Mazarei, Elham
A1 - Penschke, Christopher
A1 - Saalfrank, Peter
T1 - Band gap engineering in two-dimensional materials by functionalization
BT - Methylation of graphene and graphene bilayers
JF - ACS Omega
N2 - Graphene is well-knownfor its unique combination of electricaland mechanical properties. However, its vanishing band gap limitsthe use of graphene in microelectronics. Covalent functionalizationof graphene has been a common approach to address this critical issueand introduce a band gap. In this Article, we systematically analyzethe functionalization of single-layer graphene (SLG) and bilayer graphene(BLG) with methyl (CH3) using periodic density functionaltheory (DFT) at the PBE+D3 level of theory. We also include a comparisonof methylated single-layer and bilayer graphene, as well as a discussionof different methylation options (radicalic, cationic, and anionic).For SLG, methyl coverages ranging from 1/8 to 1/1, (i.e.,the fully methylated analogue of graphane) are considered. We findthat up to a coverage theta of 1/2, graphene readily accepts CH3, with neighbor CH3 groups preferring trans positions. Above theta = 1/2, the tendency to accept further CH3 weakens and the lattice constant increases. The band gapbehaves less regularly, but overall it increases with increasing methylcoverage. Thus, methylated graphene shows potential for developingband gap-tuned microelectronics devices and may offer further functionalizationoptions. To guide in the interpretation of methylation experiments,vibrational signatures of various species are characterized by normal-modeanalysis (NMA), their vibrational density of states (VDOS), and infrared(IR) spectra, the latter two are obtained from ab initio moleculardynamics (AIMD) in combination with a velocity-velocity autocorrelationfunction (VVAF) approach.
KW - Adsorption
KW - Alkyls
KW - Band structure
KW - Electrical conductivity
KW - Two dimensional materials
Y1 - 2023
U6 - https://doi.org/10.1021/acsomega.3c02068
SN - 2470-1343
VL - 8
IS - 24
SP - 22026
EP - 22041
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Koch, Andreas
T1 - The multiple bond character of the carbon-boron bond in boron trapped N-heterocyclic carbenes (NHCs) and cyclic(alkyl)(amino) carbenes (CAACs) on the magnetic criterion
JF - Tetrahedron
N2 - Geometry, 11B, 13C chemical shifts and the spatial magnetic properties (Through-Space NMR Shieldings -TSNMRS) of both cations and anions of boron-trapped N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (CAACs) and of the corresponding diborane/diborene/diboryne dis-carbene adducts have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept; the TSNMRS results are visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The ICSS of the TSNMRS (actually the anisotropy effects measurable in 1H NMR spectroscopy) are employed to qualify and quantify the present multiple bond character of the Carbene-Boron bond in the trapped NHCs and CAACs. Results are confirmed by bond length and 11B/13C chemical shift variations. Thus the partial multiple bond character of the Carbene-Boron bond cannot be expressed by the arrow of weak, much longer dative bonds and should be omitted as in other covalent lone pair-it or triel bonds. & COPY; 2023 Elsevier Ltd. All rights reserved.
KW - NHCs
KW - CAACs
KW - Multiple NHC(CAAC)-Boron bonds
KW - Through -space NMR
KW - shieldings (TSNMRS)
KW - NICS
KW - Anisotropy effect
KW - Ring current effect
Y1 - 2023
U6 - https://doi.org/10.1016/j.tet.2023.133469
SN - 0040-4020
SN - 1464-5416
VL - 140
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Schlappa, Stephanie
A1 - Bressel, Lena
A1 - Reich, Oliver
A1 - Münzberg, Marvin
T1 - Advanced particle size analysis in high-solid-content polymer dispersions using photon density wave spectroscopy
JF - Polymers
N2 - High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12-55% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (X-2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques.
KW - emulsion polymerization
KW - multiple light scattering
KW - photon density wave
KW - spectroscopy
KW - particle sizing
KW - swelling of polymers
Y1 - 2023
U6 - https://doi.org/10.3390/polym15153181
SN - 2073-4360
VL - 15
IS - 15
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Xu, Yaolin
A1 - Dong, Kang
A1 - Jie, Yulin
A1 - Adelhelm, Philipp
A1 - Chen, Yawei
A1 - Xu, Liang
A1 - Yu, Peiping
A1 - Kim, Junghwa
A1 - Kochovski, Zdravko
A1 - Yu, Zhilong
A1 - Li, Wanxia
A1 - LeBeau, James
A1 - Shao-Horn, Yang
A1 - Cao, Ruiguo
A1 - Jiao, Shuhong
A1 - Cheng, Tao
A1 - Manke, Ingo
A1 - Lu, Yan
T1 - Promoting mechanistic understanding of lithium deposition and solid-electrolyte interphase (SEI) formation using advanced characterization and simulation methods: recent progress, limitations, and future perspectives
JF - Avanced energy materials
N2 - In recent years, due to its great promise in boosting the energy density of lithium batteries for future energy storage, research on the Li metal anode, as an alternative to the graphite anode in Li-ion batteries, has gained significant momentum. However, the practical use of Li metal anodes has been plagued by unstable Li (re)deposition and poor cyclability. Although tremendous efforts have been devoted to the stabilization of Li metal anodes, the mechanisms of electrochemical (re-)deposition/dissolution of Li and solid-electrolyte-interphase (SEI) formation remain elusive. This article highlights the recent mechanistic understandings and observations of Li deposition/dissolution and SEI formation achieved from advanced characterization techniques and simulation methods, and discusses major limitations and open questions in these processes. In particular, the authors provide their perspectives on advanced and emerging/potential methods for obtaining new insights into these questions. In addition, they give an outlook into cutting-edge interdisciplinary research topics for Li metal anodes. It pushes beyond the current knowledge and is expected to accelerate development toward a more in-depth and comprehensive understanding, in order to guide future research on Li metal anodes toward practical application.
KW - advanced characterization
KW - Li deposition
KW - Li dissolution
KW - Li metal
KW - anodes
KW - mechanistic understanding
KW - solid-electrolyte-interphase
KW - theoretical simulation
Y1 - 2022
U6 - https://doi.org/10.1002/aenm.202200398
SN - 1614-6832
SN - 1614-6840
VL - 12
IS - 19
PB - Wiley
CY - Weinheim
ER -
TY - JOUR
A1 - Rothe, Martin
A1 - Zhao, Yuhang
A1 - Müller, Johannes
A1 - Kewes, Günter
A1 - Koch, Christoph T.
A1 - Lu, Yan
A1 - Benson, Oliver
T1 - Self-assembly of plasmonic nanoantenna-waveguide structures for subdiffractional chiral sensing
JF - ACS nano
N2 - Spin-momentum locking is a peculiar effect in the near-field of guided optical or plasmonic modes. It can be utilized to map the spinning or handedness of electromagnetic fields onto the propagation direction. This motivates a method to probe the circular dichroism of an illuminated chiral object. In this work, we demonstrate local, subdiffraction limited chiral coupling of light and propagating surface plasmon polaritons in a self-assembled system of a gold nanoantenna and a silver nanowire. A thin silica shell around the nanowire provides precise distance control and also serves as a host for fluorescent molecules, which indicate the direction of plasmon propagation. We characterize our nanoantenna-nanowire systems comprehensively through correlated electron microscopy, energy-dispersive X-ray spectroscopy, dark-field, and fluorescence imaging. Three-dimensional numerical simulations support the experimental findings. Besides our measurement of far-field polarization, we estimate sensing capabilities and derive not only a sensitivity of 1 mdeg for the ellipticity of the light field, but also find 10(3) deg cm(2)/dmol for the circular dichroism of an analyte locally introduced in the hot spot of the antenna-wire system. Thorough modeling of a prototypical design predicts on-chip sensing of chiral analytes. This introduces our system as an ultracompact sensor for chiral response far below the diffraction limit.
KW - plasmonics
KW - nanoparticle assemblies
KW - core-shell
KW - spin-orbit coupling
KW - chirality
KW - circular dichroism
KW - nano-optics
Y1 - 2021
U6 - https://doi.org/10.1021/acsnano.0c05240
SN - 1936-0851
SN - 1936-086X
VL - 15
IS - 1
SP - 351
EP - 361
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Ning, Jiaoyi
A1 - Yu, Hongtao
A1 - Mei, Shilin
A1 - Schütze, Yannik
A1 - Risse, Sebastian
A1 - Kardjilov, Nikolay
A1 - Hilger, André
A1 - Manke, Ingo
A1 - Bande, Annika
A1 - Ruiz, Victor G.
A1 - Dzubiella, Joachim
A1 - Meng, Hong
A1 - Lu, Yan
T1 - Constructing binder- and carbon additive-free organosulfur cathodes based on conducting thiol-polymers through electropolymerization for lithium-sulfur batteries
JF - ChemSusChem
N2 - Herein, the concept of constructing binder- and carbon additive-free organosulfur cathode was proved based on thiol-containing conducting polymer poly(4-(thiophene-3-yl) benzenethiol) (PTBT). The PTBT featured the polythiophene-structure main chain as a highly conducting framework and the benzenethiol side chain to copolymerize with sulfur and form a crosslinked organosulfur polymer (namely S/PTBT). Meanwhile, it could be in-situ deposited on the current collector by electro-polymerization, making it a binder-free and free-standing cathode for Li-S batteries. The S/PTBT cathode exhibited a reversible capacity of around 870 mAh g(-1) at 0.1 C and improved cycling performance compared to the physically mixed cathode (namely S&PTBT). This multifunction cathode eliminated the influence of the additives (carbon/binder), making it suitable to be applied as a model electrode for operando analysis. Operando X-ray imaging revealed the remarkable effect in the suppression of polysulfides shuttle via introducing covalent bonds, paving the way for the study of the intrinsic mechanisms in Li-S batteries.
KW - electrochemistry
KW - energy storage
KW - lithium-sulfur batteries
KW - operando
KW - studies
KW - organosulfur
Y1 - 2022
U6 - https://doi.org/10.1002/cssc.202200434
SN - 1864-5631
SN - 1864-564X
VL - 15
IS - 14
PB - Wiley
CY - Weinheim
ER -
TY - JOUR
A1 - Lau, Skadi
A1 - Liu, Yue
A1 - Maier, Anna
A1 - Braune, Steffen
A1 - Gossen, Manfred
A1 - Neffe, Axel T.
A1 - Lendlein, Andreas
T1 - Establishment of an in vitro thrombogenicity test system with cyclic olefin copolymer substrate for endothelial layer formation
JF - MRS communications / a publication of the Materials Research Society
N2 - In vitro thrombogenicity test systems require co-cultivation of endothelial cells and platelets under blood flow-like conditions. Here, a commercially available perfusion system is explored using plasma-treated cyclic olefin copolymer (COC) as a substrate for the endothelial cell layer. COC was characterized prior to endothelialization and co-cultivation with platelets under static or flow conditions. COC exhibits a low roughness and a moderate hydrophilicity. Flow promoted endothelial cell growth and prevented platelet adherence. These findings show the suitability of COC as substrate and the importance of blood flow-like conditions for the assessment of the thrombogenic risk of drugs or cardiovascular implant materials.
Y1 - 2021
U6 - https://doi.org/10.1557/s43579-021-00072-6
SN - 2159-6867
VL - 11
IS - 5
SP - 559
EP - 567
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Neusser, David
A1 - Sun, Bowen
A1 - Tan, Wen Liang
A1 - Thomsen, Lars
A1 - Schultz, Thorsten
A1 - Perdigon-Toro, Lorena
A1 - Koch, Norbert
A1 - Shoaee, Safa
A1 - McNeill, Christopher R.
A1 - Neher, Dieter
A1 - Ludwigs, Sabine
T1 - Spectroelectrochemically determined energy levels of PM6:Y6 blends and their relevance to solar cell performance
JF - Journal of materials chemistry : C, Materials for optical and electronic devices
N2 - Recent advances in organic solar cell performance have been mainly driven forward by combining high-performance p-type donor-acceptor copolymers (e.g.PM6) and non-fullerene small molecule acceptors (e.g.Y6) as bulk-heterojunction layers. A general observation in such devices is that the device performance, e.g., the open-circuit voltage, is strongly dependent on the processing solvent. While the morphology is a typically named key parameter, the energetics of donor-acceptor blends are equally important, but less straightforward to access in the active multicomponent layer. Here, we propose to use spectral onsets during electrochemical cycling in a systematic spectroelectrochemical study of blend films to access the redox behavior and the frontier orbital energy levels of the individual compounds. Our study reveals that the highest occupied molecular orbital offset (Delta E-HOMO) in PM6:Y6 blends is similar to 0.3 eV, which is comparable to the binding energy of Y6 excitons and therefore implies a nearly zero driving force for the dissociation of Y6 excitons. Switching the PM6 orientation in the blend films from face-on to edge-on in bulk has only a minor influence on the positions of the energy levels, but shows significant differences in the open circuit voltage of the device. We explain this phenomenon by the different interfacial molecular orientations, which are known to affect the non-radiative decay rate of the charge-transfer state. We compare our results to ultraviolet photoelectron spectroscopy data, which shows distinct differences in the HOMO offsets in the PM6:Y6 blend compared to neat films. This highlights the necessity to measure the energy levels of the individual compounds in device-relevant blend films.
Y1 - 2022
U6 - https://doi.org/10.1039/d2tc01918c
SN - 2050-7526
SN - 2050-7534
VL - 10
IS - 32
SP - 11565
EP - 11578
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Tung, Wing Tai
A1 - Sun, Xianlei
A1 - Wang, Weiwei
A1 - Xu, Xun
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films
JF - MRS advances : a journal of the Materials Research Society (MRS)
N2 - The capability of a degradable implant to provide mechanical support depends on its degradation behavior. Hydrolytic degradation was studied for a polyesteretherurethane (PEEU70), which consists of poly(p-dioxanone) (PPDO) and poly(epsilon-caprolactone) (PCL) segments with a weight ratio of 70:30 linked by diurethane junction units. PEEU70 samples prepared in the form of meshes with average fiber diameters of 1.5 mu m (mesh1.5) and 1.2 mu m (mesh1.2), and films were sterilized and incubated in PBS at 37 degrees C with 5 vol% CO2 supply for 1 to 6 weeks. Degradation features, such as cracks or wrinkles, became apparent from week 4 for all samples. Mass loss was found to be 11 wt%, 6 wt%, and 4 wt% for mesh1.2, mesh1.5, and films at week 6. The elongation at break decreased to under 20% in two weeks for mesh1.2. In case of the other two samples, this level of degradation was achieved after 4 weeks. The weight average molecular weight of both PEEU70 mesh and film samples decreased to below 30 kg/mol when elongation at break dropped below 20%. The time period of sustained mechanical stability of PEEU70-based meshes depends on the fiber diameter and molecular weight.
Y1 - 2021
U6 - https://doi.org/10.1557/s43580-020-00001-0
SN - 2059-8521
VL - 6
IS - 10
SP - 276
EP - 282
PB - Springer Nature Switzerland AG
CY - Cham
ER -
TY - JOUR
A1 - Stefancu, Andrei
A1 - Nan, Lin
A1 - Zhu, Li
A1 - Chis, Vasile
A1 - Bald, Ilko
A1 - Liu, Min
A1 - Leopold, Nicolae
A1 - Maier, Stefan A.
A1 - Cortes, Emiliano
T1 - Controlling plasmonic chemistry pathways through specific ion effects
JF - Advanced optical materials
N2 - Plasmon-driven dehalogenation of brominated purines has been recently explored as a model system to understand fundamental aspects of plasmon-assisted chemical reactions. Here, it is shown that divalent Ca2+ ions strongly bridge the adsorption of bromoadenine (Br-Ade) to Ag surfaces.
Such ion-mediated binding increases the molecule's adsorption energy leading to an overlap of the metal energy states and the molecular states, enabling the chemical interface damping (CID) of the plasmon modes of the Ag nanostructures (i.e., direct electron transfer from the metal to Br-Ade).
Consequently, the conversion of Br-Ade to adenine almost doubles following the addition of Ca2+.
These experimental results, supported by theoretical calculations of the local density of states of the Ag/Br-Ade complex, indicate a change of the charge transfer pathway driving the dehalogenation reaction, from Landau damping (in the lack of Ca2+ ions) to CID (after the addition of Ca2+).
The results show that the surface dynamics of chemical species (including water molecules) play an essential role in charge transfer at plasmonic interfaces and cannot be ignored. It is envisioned that these results will help in designing more efficient nanoreactors, harnessing the full potential of plasmon-assisted chemistry.
KW - chemical interface damping
KW - Hofmeister effect
KW - hydration layer
KW - plasmonic chemistry
KW - specific ion effects
KW - surface-enhanced Raman scattering
Y1 - 2022
U6 - https://doi.org/10.1002/adom.202200397
SN - 2195-1071
VL - 10
IS - 14
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Banerji, Amitabh
A1 - Thyssen, Christoph
A1 - Pampel, Barbara
A1 - Huwer, Johannes
T1 - Naturwissenschaftsunterricht und Informatik
BT - bringt zusammen, was zusammen gehört?!
BT - bringing together, what belongs together?!
JF - Chemie konkret : CHEMKON ; Forum für Unterricht und Didaktik
N2 - Computer literacy plays an increasingly important role in the education of 21st-century society. For chemistry' education. this results in two aspects: On the one hand. informatics education concepts can help to promote chemistry- and science-specific ways of thinking and working. On the other hand, chemistry education can contribute to information education. This paper addresses both aspects and tries to point out the Mutual benefits of informatics education and science education with regards to chemistry lessons.
N2 - Informatische Bildung spielt eine immer zentralere Rolle in der Bildung einer Gesellschaft des 21. Jahrhunderts. Für den Chemieunterricht ergeben sich daraus zwei Aspekte: Einerseits können Konzepte der informatischen Bildung dabei helfen, chemie- und naturwissenschaftsspezifische Denk- und Arbeitsweisen zu fördern. Andererseits kann der Chemieunterricht einen Beitrag für die informatische Bildung leisten. Dieser Artikel geht auf beide Aspekte ein und versucht die gegenseitigen Vorteile der informatischen Bildung und der naturwissenschaftlichen Bildung im Chemieunterricht darzustellen.
T2 - Science education and computer literacy
KW - computer literacy
KW - scientific literacy
KW - informatische Bildung
KW - naturwissenschaftliche Bildung
Y1 - 2021
U6 - https://doi.org/10.1002/ckon.202100008
SN - 0944-5846
SN - 1521-3730
VL - 28
IS - 6
SP - 263
EP - 265
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Zhao, Yuhang
A1 - Opitz, Andreas
A1 - Eljarrat, Alberto
A1 - Kochovski, Zdravko
A1 - Koch, Christoph
A1 - Koch, Norbert
A1 - Lu, Yan
T1 - Kinetic study on the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane on Ag nanoparticles in chloroform
BT - implications for the charge transfer complex of Ag-F(4)TCNQ
JF - ACS applied nano materials
N2 - In this study, the kinetics of the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ) on the surface of Ag nanoparticles (Ag NPs) in chloroform has been intensively investigated, as molecular doping is known to play a crucial role in organic electronic devices. Based on the results obtained from UV-visible (vis)-near-infrared (NIR) absorption spectroscopy, cryogenic transmission electron microscopy, scanning nanobeam electron diffraction, and electron energy loss spectroscopy, a two-step interaction kinetics has been proposed for the Ag NPs and F(4)TCNQ molecules, which includes the first step of electron transfer from Ag NPs to F(4)TCNQ indicated by the ionization of F(4)TCNQ and the second step of the formation of a Ag-F(4)TCNQ complex. The whole process has been followed via UV-vis-NIR absorption spectroscopy, which reveals distinct kinetics at two stages: the instantaneous ionization and the long-term complex formation. The kinetics and the influence of the molar ratio of Ag NPs/F(4)TCNQ molecules on the interaction between Ag NPs and F(4)TCNQ molecules in an organic solution are reported herein for the first time. Furthermore, the control experiment with silica-coated Ag NPs manifests that the charge transfer at the surface between Ag NPs and F(4)TCNQ molecules is prohibited by a silica layer of 18 nm.
KW - Ag nanoparticles
KW - F(4)TCNQ
KW - phase transfer
KW - kinetics
KW - electron transfer
KW - surface interaction
Y1 - 2021
U6 - https://doi.org/10.1021/acsanm.1c02153
SN - 2574-0970
VL - 4
IS - 11
SP - 11625
EP - 11635
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Zhou, Shuo
A1 - Xu, Xun
A1 - Ma, Nan
A1 - Jung, Friedrich
A1 - Lendlein, Andreas
T1 - Influence of sterilization conditions on sulfate-functionalized polyGGE
JF - Clinical hemorheology and microcirculation : blood flow and vessels
N2 - Sulfated biomolecules are known to influence numerous biological processes in all living organisms. Particularly, they contribute to prevent and inhibit the hypercoagulation condition. The failure of polymeric implants and blood contacting devices is often related to hypercoagulation and microbial contamination. Here, bioactive sulfated biomacromolecules are mimicked by sulfation of poly(glycerol glycidyl ether) (polyGGE) films. Autoclaving, gamma-ray irradiation and ethylene oxide (EtO) gas sterilization techniques were applied to functionalized materials. The sulfate group density and hydrophilicity of sulfated polymers were decreased while chain mobility and thermal degradation were enhanced post autoclaving when compared to those after EtO sterilization. These results suggest that a quality control after sterilization is mandatory to ensure the amount and functionality of functionalized groups are retained.
KW - Sulfated polymer
KW - sulfation
KW - sterilization
KW - ethylene oxide
Y1 - 2021
U6 - https://doi.org/10.3233/CH-211241
SN - 1386-0291
SN - 1875-8622
VL - 79
IS - 4
SP - 597
EP - 608
PB - IOS Press
CY - Amsterdam
ER -
TY - JOUR
A1 - Michaelis, Vivien
A1 - Aengenheister, Leonie
A1 - Tuchtenhagen, Max
A1 - Rinklebe, Jörg
A1 - Ebert, Franziska
A1 - Schwerdtle, Tanja
A1 - Buerki-Thurnherr, Tina
A1 - Bornhorst, Julia
T1 - Differences and interactions in placental manganese and iron transfer across an in vitro model of human villous trophoblasts
JF - International journal of molecular sciences
N2 - Manganese (Mn) as well as iron (Fe) are essential trace elements (TE) important for the maintenance of physiological functions including fetal development. However, in the case of Mn, evidence suggests that excess levels of intrauterine Mn are associated with adverse pregnancy outcomes. Although Mn is known to cross the placenta, the fundamentals of Mn transfer kinetics and mechanisms are largely unknown. Moreover, exposure to combinations of TEs should be considered in mechanistic transfer studies, in particular for TEs expected to share similar transfer pathways. Here, we performed a mechanistic in vitro study on the placental transfer of Mn across a BeWo b30 trophoblast layer. Our data revealed distinct differences in the placental transfer of Mn and Fe. While placental permeability to Fe showed a clear inverse dose-dependency, Mn transfer was largely independent of the applied doses. Concurrent exposure of Mn and Fe revealed transfer interactions of Fe and Mn, indicating that they share common transfer mechanisms. In general, mRNA and protein expression of discussed transporters like DMT1, TfR, or FPN were only marginally altered in BeWo cells despite the different exposure scenarios highlighting that Mn transfer across the trophoblast layer likely involves a combination of active and passive transport processes.
KW - manganese
KW - iron
KW - placental transfer
KW - TE interactions
KW - BeWo b30
KW - trophoblasts
Y1 - 2022
U6 - https://doi.org/10.3390/ijms23063296
SN - 1422-0067
VL - 23
IS - 6
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Bande, Annika
A1 - González, Leticia
A1 - Klamroth, Tillmann
A1 - Tremblay, Jean Christophe
T1 - Theoretical chemistry and quantum dynamics at interfaces
BT - Celebrating the career of Peter Saalfrank on the occasion of his 60th birthday
T2 - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
Y1 - 2022
U6 - https://doi.org/10.1016/j.chemphys.2022.111509
SN - 0301-0104
SN - 1873-4421
VL - 558
PB - Elsevier Science
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Crovetto, Andrea
A1 - Kojda, Sandrino Danny
A1 - Yi, Feng
A1 - Heinselman, Karen N.
A1 - LaVan, David A.
A1 - Habicht, Klaus
A1 - Unold, Thomas
A1 - Zakutayev, Andriy
T1 - Crystallize It before It diffuses
BT - kinetic stabilization of thin-film phosphorus-rich semiconductor CuP2
JF - Journal of the american chemical society
N2 - Numerous phosphorus-rich metal phosphides containing both P-P bonds and metal-P bonds are known from the solid-state chemistry literature. A method to grow these materials in thin-film form would be desirable, as thin films are required in many applications and they are an ideal platform for high-throughput studies. In addition, the high density and smooth surfaces achievable in thin films are a significant advantage for characterization of transport and optical properties. Despite these benefits, there is hardly any published work on even the simplest binary phosphorus-rich phosphide films. Here, we demonstrate growth of single-phase CuP2 films by a two-step process involving reactive sputtering of amorphous CuP2+x and rapid annealing in an inert atmosphere. At the crystallization temperature, CuP2 is thermodynamically unstable with respect to Cu3P and P-4. However, CuP2 can be stabilized if the amorphous precursors are mixed on the atomic scale and are sufficiently close to the desired composition (neither too P poor nor too P rich). Fast formation of polycrystalline CuP2, combined with a short annealing time, makes it possible to bypass the diffusion processes responsible for decomposition. We find that thin-film CuP2 is a 1.5 eV band gap semiconductor with interesting properties, such as a high optical absorption coefficient (above 10(5) cm(-1)), low thermal conductivity (1.1 W/(K m)), and composition-insensitive electrical conductivity (around 1 S/cm). We anticipate that our processing route can be extended to other phosphorus-rich phosphides that are still awaiting thin-film synthesis and will lead to a more complete understanding of these materials and of their potential applications.
Y1 - 2022
U6 - https://doi.org/10.1021/jacs.2c04868
SN - 0002-7863
SN - 1520-5126
VL - 144
IS - 29
SP - 13334
EP - 13343
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Tung, Wing Tai
A1 - Maring, Janita A.
A1 - Xu, Xun
A1 - Liu, Yue
A1 - Becker, Matthias
A1 - Somesh, Dipthi Bachamanda
A1 - Klose, Kristin
A1 - Wang, Weiwei
A1 - Sun, Xianlei
A1 - Ullah, Imran
A1 - Kratz, Karl
A1 - Neffe, Axel T.
A1 - Stamm, Christof
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - In vivo performance of a cell and factor free multifunctional fiber mesh modulating postinfarct myocardial remodeling
JF - Advanced Functional Materials
N2 - Guidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post-MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28-32%) and increased wall thickness (854 mu m vs 400-600 mu m), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7-31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.
KW - bioinstructive materials
KW - cardiac regeneration
KW - function by structure;
KW - modulation of in vivo regeneration
KW - multifunctional biomaterials
Y1 - 2022
U6 - https://doi.org/10.1002/adfm.202110179
SN - 1616-301X
SN - 1616-3028
VL - 32
IS - 31
PB - Wiley
CY - Weinheim
ER -
TY - JOUR
A1 - Breternitz, Joachim
A1 - Schorr, Susan
T1 - Symmetry relations in wurtzite nitrides and oxide nitrides and the curious case of Pmc2(1)
JF - Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances
N2 - Binary III-V nitrides such as AlN, GaN and InN in the wurtzite-type structure have long been considered as potent semiconducting materials because of their optoelectronic properties, amongst others. With rising concerns over the utilization of scarce elements, a replacement of the trivalent cations by others in ternary and multinary nitrides has led to the development of different variants of nitrides and oxide nitrides crystallizing in lower-symmetry variants of wurtzite. This work presents the symmetry relationships between these structural types specific to nitrides and oxide nitrides and updates some prior work on this matter. The non-existence of compounds crystallizing in Pmc2(1), formally the highest subgroup of the wurtzite type fulfilling Pauling's rules for 1:1:2 stoichiometries, has been puzzling scientists for a while; a rationalization is given, from a crystallographic basis, of why this space group is unlikely to be adopted.
KW - group-subgroup relationships
KW - nitride materials
KW - wurtzite type
Y1 - 2021
U6 - https://doi.org/10.1107/S2053273320015971
SN - 2053-2733
VL - 77
IS - 3
SP - 208
EP - 216
PB - Blackwell
CY - Oxford [u.a.]
ER -
TY - JOUR
A1 - Mei, Shilin
A1 - Siebert, Andreas
A1 - Xu, Yaolin
A1 - Quan, Ting
A1 - Garcia-Diez, Raul
A1 - Bär, Marcus
A1 - Härtel, Paul
A1 - Abendroth, Thomas
A1 - Dörfler, Susanne
A1 - Kaskel, Stefan
A1 - Lu, Yan
T1 - Large-Scale Synthesis of Nanostructured Carbon-Ti4O7 Hollow Particles as Efficient Sulfur Host Materials for Multilayer Lithium-Sulfur Pouch Cells
JF - Batteries & supercaps
N2 - Applications of advanced cathode materials with well-designed chemical components and/or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium-sulfur (Li-S) batteries under practical working conditions, one long-term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles (Ti4O7) using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro- & mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C-Ti4O7 based pouch cell endows a high discharge capacity of 1003 mAhg(-1) at 0.05 C, a high-capacity retention of 83.7% after 100 cycles at 0.1 C, and a high Coulombic efficiency of 97.5% at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab- to large-scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li-S pouch cells.
KW - lithium-sulfur batteries
KW - pouch cell
KW - spherical polyelectrolyte brushes (SPB)
KW - Ti4O7
Y1 - 2022
U6 - https://doi.org/10.1002/batt.202100398
SN - 2566-6223
VL - 5
IS - 6
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Lepre, Enrico
A1 - Heske, Julian
A1 - Nowakowski, Michal
A1 - Scoppola, Ernesto
A1 - Zizak, Ivo
A1 - Heil, Tobias
A1 - Kühne, Thomas D.
A1 - Antonietti, Markus
A1 - Lopez-Salas, Nieves
A1 - Albero, Josep
T1 - Ni-based electrocatalysts for unconventional CO2 reduction reaction to formic acid
JF - Nano energy
N2 - Electrochemical reduction stands as an alternative to revalorize CO2. Among the different alternatives, Ni single atoms supported on carbonaceous materials are an appealing catalytic solution due to the low cost and versatility of the support and the optimal usage of Ni and its predicted selectivity and efficiency (ca. 100% towards CO). Herein, we have used noble carbonaceous support derived from cytosine to load Ni subnanometric sites. The large heteroatom content of the support allows the stabilization of up to 11 wt% of Ni without the formation of nanoparticles through a simple impregnation plus calcination approach, where nickel promotes the stabilization of C3NOx frameworks and the oxidative support promotes a high oxidation state of nickel. EXAFS analysis points at nickel single atoms or subnanometric clusters coordinated by oxygen in the material surface. Unlike the wellknown N-coordinated Ni single sites selectivity towards CO2 reduction, O-coordinated-Ni single sites (ca. 7 wt% of Ni) reduced CO2 to CO, but subnanometric clusters (11 wt% of Ni) foster the unprecedented formation of HCOOH with 27% Faradaic efficiency at - 1.4 V. Larger Ni amounts ended up on the formation of NiO nanoparticles and almost 100% selectivity towards hydrogen evolution.
KW - CO 2 reduction reaction
KW - Noble carbon
KW - Ni-O4 electrocatalysts
KW - Formic acid
Y1 - 2022
U6 - https://doi.org/10.1016/j.nanoen.2022.107191
SN - 2211-2855
SN - 2211-3282
VL - 97
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Haubitz, Toni
A1 - Drobot, Björn
A1 - Tsushima, Satoru
A1 - Steudtner, Robin
A1 - Stumpf, Thorsten
A1 - Kumke, Michael Uwe
T1 - Quenching mechanism of uranyl(VI) by chloride and bromide in aqueous and non-aqueous solutions
JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2 - A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl-halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X-2(center dot-) and the formed uranyl(V) into fully solvated ions, thereby "reigniting" U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-to-metal charge transfer is strongly reduced in acetonitrile.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.jpca.1c02487
SN - 1089-5639
SN - 1520-5215
VL - 125
IS - 20
SP - 4380
EP - 4389
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Pham, Duong Tung
A1 - Quan, Ting
A1 - Mei, Shilin
A1 - Lu, Yan
T1 - Colloidal metal sulfide nanoparticles for high performance electrochemical energy storage systems
JF - Current opinion in green and sustainable chemistry
N2 - Transition metal sulfides have emerged as excellent replacement candidates of traditional insertion electrode materials based on their conversion or alloying mechanisms, facilitating high specific capacity and rate ability. However, parasitic reactions such as massive volume change during the discharge/ charge processes, intermediate polysulfide dissolution, and passivating solid electrolyte interface formation have led to poor cyclability, hindering their feasibility and applicability in energy storage systems. Colloidal metal sulfide nanoparticles, a special class that integrates the intrinsic chemical properties of metal sulfides and their specified structural features, have fairly enlarged their contribution due to the synergistic effect. This review highlights the latest synthetic approaches based on colloidal process. Their corresponding electrochemical outcomes will also be discussed, which are thoroughly updated along with their insight scientific standpoints.
Y1 - 2022
U6 - https://doi.org/10.1016/j.cogsc.2022.100596
SN - 2452-2236
VL - 34
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Reitenbach, Julija
A1 - Geiger, Christina
A1 - Wang, Peixi
A1 - Vagias, Apostolos N.
A1 - Cubitt, Robert
A1 - Schanzenbach, Dirk
A1 - Laschewsky, André
A1 - Papadakis, Christine M.
A1 - Müller-Buschbaum, Peter
T1 - Effect of magnesium salts with chaotropic anions on the swelling behavior of PNIPMAM thin films
JF - Macromolecules : a publication of the American Chemical Society
N2 - Poly(N-isopropylmethacrylamide) (PNIPMAM) is a stimuli responsive polymer, which in thin film geometry exhibits a volume-phase transition upon temperature increase in water vapor. The swelling behavior of PNIPMAM thin films containing magnesium salts in water vapor is investigated in view of their potential application as nanodevices. Both the extent and the kinetics of the swelling ratio as well as the water content are probed with in situ time-of-flight neutron reflectometry. Additionally, in situ Fourier-transform infrared (FTIR) spectroscopy provides information about the local solvation of the specific functional groups, while two-dimensional FTIR correlation analysis further elucidates the temporal sequence of solvation events. The addition of Mg(ClO4)2 or Mg(NO3)2 enhances the sensitivity of the polymer and therefore the responsiveness of switches and sensors based on PNIPMAM thin films. It is found that Mg(NO3)2 leads to a higher relative water uptake and therefore achieves the highest thickness gain in the swollen state.
Y1 - 2023
U6 - https://doi.org/10.1021/acs.macromol.2c02282
SN - 0024-9297
SN - 1520-5835
VL - 56
IS - 2
SP - 567
EP - 577
PB - American Chemical Society
CY - Washington
ER -
TY - CHAP
A1 - Breternitz, Joachim
A1 - Schorr, Susan
T1 - Halide perovskites
BT - structural systematisation and what we learn from it
T2 - Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances
KW - halide perovskites
KW - semiconductors
KW - group-subgroup relations
KW - twinning
Y1 - 2021
U6 - https://doi.org/10.1107/S0108767321089479
SN - 2053-2733
VL - 77
IS - Suppl.
SP - C750
EP - C750
PB - Blackwell
CY - Oxford [u.a.]
ER -
TY - JOUR
A1 - Nchiozem-Ngnitedem, Vaderament-Alexe
A1 - Sperlich, Eric
A1 - Matieta, Valaire Yemene
A1 - Kuete, Jenifer Reine Ngnouzouba
A1 - Kuete, Victor
A1 - Omer, Ejlal A. A.
A1 - Efferth, Thomas
A1 - Schmidt, Bernd
T1 - Synthesis and bioactivity of isoflavones from ficus carica and some non-natural analogues
JF - Journal of natural products : Lloydia
N2 - FicucariconeD (1) and its 4 '-demethyl congener 2 are isoflavones isolated from fruits of Ficus carica that share a 5,7-dimethoxy-6-prenyl-substituted A-ring. Both naturalproducts were, for the first time, obtained by chemical synthesisin six steps, starting from 2,4,6-trihydroxyacetophenone. Key stepsare a microwave-promoted tandem sequence of Claisen- and Cope-rearrangementsto install the 6-prenyl substituent and a Suzuki-Miyaura crosscoupling for installing the B-ring. By using various boronic acids,non-natural analogues become conveniently available. All compoundswere tested for cytotoxicity against drug-sensitive and drug-resistanthuman leukemia cell lines, but were found to be inactive. The compoundswere also tested for antimicrobial activities against a panel of eightGram-negative and two Gram-positive bacterial strains. Addition ofthe efflux pump inhibitor phenylalanine-arginine-beta-naphthylamide(PA beta N) significantly improved the antibiotic activity in mostcases, with MIC values as low as 2.5 mu M and activity improvementfactors as high as 128-fold.
KW - Antimicrobial activity
KW - Bacteria
KW - Ethers
KW - Flavonoids
KW - Mixtures
Y1 - 2023
U6 - https://doi.org/10.1021/acs.jnatprod.3c00219
SN - 0163-3864
SN - 1520-6025
VL - 86
IS - 6
SP - 1520
EP - 1528
PB - American Chemical Society
CY - Washington, DC
ER -
TY - JOUR
A1 - Geiger, Christina
A1 - Reitenbach, Julija
A1 - Henschel, Cristiane
A1 - Kreuzer, Lucas
A1 - Widmann, Tobias
A1 - Wang, Peixi
A1 - Mangiapia, Gaetano
A1 - Moulin, Jean-François
A1 - Papadakis, Christine M.
A1 - Laschewsky, André
A1 - Müller-Buschbaum, Peter
T1 - Ternary nanoswitches realized with multiresponsive PMMA-b-PNIPMAM films in mixed water/acetone vapor atmospheres
JF - Advanced engineering materials
N2 - To systematically add functionality to nanoscale polymer switches, an understanding of their responsive behavior is crucial. Herein, solvent vapor stimuli are applied to thin films of a diblock copolymer consisting of a short poly(methyl methacrylate) (PMMA) block and a long poly(N-isopropylmethacrylamide) (PNIPMAM) block for realizing ternary nanoswitches. Three significantly distinct film states are successfully implemented by the combination of amphiphilicity and co-nonsolvency effect. The exposure of the thin films to nitrogen, pure water vapor, and mixed water/acetone (90 vol%/10 vol%) vapor switches the films from a dried to a hydrated (solvated and swollen) and a water/acetone-exchanged (solvated and contracted) equilibrium state. These three states have distinctly different film thicknesses and solvent contents, which act as switch positions "off," "on," and "standby." For understanding the switching process, time-of-flight neutron reflectometry (ToF-NR) and spectral reflectance (SR) studies of the swelling and dehydration process are complemented by information on the local solvation of functional groups probed with Fourier-transform infrared (FTIR) spectroscopy. An accelerated responsive behavior beyond a minimum hydration/solvation level is attributed to the fast build-up and depletion of the hydration shell of PNIPMAM, caused by its hydrophobic moieties promoting a cooperative hydration character.
KW - co-nonsolvency
KW - diblock copolymers
KW - nanoswitches
KW - neutron reflectometry
KW - thin films
Y1 - 2021
U6 - https://doi.org/10.1002/adem.202100191
SN - 1438-1656
SN - 1527-2648
VL - 23
IS - 11
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Melani, Giacomo
A1 - Nagata, Yuki
A1 - Saalfrank, Peter
T1 - Vibrational energy relaxation of interfacial OH on a water-covered alpha-Al2O3(0001) surface
BT - a non-equilibrium ab initio molecular dynamics study
JF - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2 - Vibrational relaxation of adsorbates is a sensitive tool to probe energy transfer at gas/solid and liquid/solid interfaces. The most direct way to study relaxation dynamics uses time-resolved spectroscopy. Here we report on a non-equilibrium ab initio molecular dynamics (NE-AIMD) methodology to model vibrational relaxation of OH vibrations on a hydroxylated, water-covered alpha-Al2O3(0001) surface. In our NE-AIMD approach, after exciting selected O-H bonds their coupling to surface phonons and to the water adlayer is analyzed in detail, by following both the energy flow in time, as well as the time-evolution of Vibrational Density of States (VDOS) curves. The latter are obtained from Time-dependent Correlation Functions (TCFs) and serve as prototypical, generic representatives of time-resolved vibrational spectra. As most important results, (i) we find a few-picosecond lifetime of the excited modes and (ii) identify both hydrogen-bonded aluminols and water molecules in the adsorbed water layer as main dissipative channels, while the direct coupling to Al2O3 surface phonons is of minor importance on the timescales of interest. Our NE-AIMD/TCF methodology is powerful for complex adsorbate systems, in principle even reacting ones, and opens a way towards time-resolved vibrational spectroscopy.
Y1 - 2021
U6 - https://doi.org/10.1039/d0cp03777j
SN - 1463-9076
SN - 1463-9084
VL - 23
IS - 13
SP - 7714
EP - 7723
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Wang, Zhenyu
A1 - Fritsch, Daniel
A1 - Berendts, Stefan
A1 - Lerch, Martin
A1 - Breternitz, Joachim
A1 - Schorr, Susan
T1 - Elucidation of the reaction mechanism for the synthesis of ZnGeN2 through Zn2GeO4 ammonolysis
JF - Chemical science / RSC, Royal Society of Chemistry
N2 - Ternary II-IV-N-2 materials have been considered as a promising class of materials that combine photovoltaic performance with earth-abundance and low toxicity. When switching from binary III-V materials to ternary II-IV-N-2 materials, further structural complexity is added to the system that may influence its optoelectronic properties. Herein, we present a systematic study of the reaction of Zn2GeO4 with NH3 that produces zinc germanium oxide nitrides, and ultimately approach stoichiometric ZnGeN2, using a combination of chemical analyses, X-ray powder diffraction and DFT calculations. Elucidating the reaction mechanism as being dominated by Zn and O extrusion at the later reaction stages, we give an insight into studying structure-property relationships in this emerging class of materials.
Y1 - 2021
U6 - https://doi.org/10.1039/d1sc00328c
SN - 2041-6539
VL - 12
IS - 24
SP - 8493
EP - 8500
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Saeedi Garakani, Sadaf
A1 - Xie, Dongjiu
A1 - Khorsand Kheirabad, Atefeh
A1 - Lu, Yan
A1 - Yuan, Jiayin
T1 - Template-synthesis of a poly(ionic liquid)-derived Fe1-xS/nitrogen-doped porous carbon membrane and its electrode application in lithium-sulfur batteries
JF - Materials advances
N2 - This study deals with the facile synthesis of Fe1-xS nanoparticle-containing nitrogen-doped porous carbon membranes (denoted as Fe1-xS/N-PCMs) via vacuum carbonization of hybrid porous poly(ionic liquid) (PIL) membranes, and their successful use as a sulfur host material to mitigate the shuttle effect in lithium-sulfur (Li-S) batteries. The hybrid porous PIL membranes as the sacrificial template were prepared via ionic crosslinking of a cationic PIL with base-neutralized 1,1 '-ferrocenedicarboxylic acid, so that the iron source was molecularly incorporated into the template. The carbonization process was investigated in detail at different temperatures, and the chemical and porous structures of the carbon products were comprehensively analyzed. The Fe1-xS/N-PCMs prepared at 900 degrees C have a multimodal pore size distribution with a satisfactorily high surface area and well-dispersed iron sulfide nanoparticles to physically and chemically confine the LiPSs. The sulfur/Fe1-xS/N-PCM composites were then tested as electrodes in Li-S batteries, showing much improved capacity, rate performance and cycle stability, in comparison to iron sulfide-free, nitrogen-doped porous carbon membranes.
Y1 - 2021
U6 - https://doi.org/10.1039/d1ma00441g
SN - 2633-5409
VL - 2
IS - 15
SP - 5203
EP - 5212
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Xu, Xun
A1 - Nie, Yan
A1 - Wang, Weiwei
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - Periodic thermomechanical modulation of toll-like receptor expression and distribution in mesenchymal stromal cells
JF - MRS communications / a publication of the Materials Research Society
N2 - Toll-like receptor (TLR) can trigger an immune response against virus including SARS-CoV-2. TLR expression/distribution is varying in mesenchymal stromal cells (MSCs) depending on their culture environments. Here, to explore the effect of periodic thermomechanical cues on TLRs, thermally controlled shape-memory polymer sheets with programmable actuation capacity were created. The proportion of MSCs expressing SARS-CoV-2-associated TLRs was increased upon stimulation. The TLR4/7 colocalization was promoted and retained in the endoplasmic reticula. The TLR redistribution was driven by myosin-mediated F-actin assembly. These results highlight the potential of boosting the immunity for combating COVID-19 via thermomechanical preconditioning of MSCs.
KW - Actuation
KW - Antiviral
KW - Biomaterial
KW - COVID-19
KW - Shape memory
Y1 - 2021
U6 - https://doi.org/10.1557/s43579-021-00049-5
SN - 2159-6867
VL - 11
IS - 4
SP - 425
EP - 431
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Schulze, Nicole
A1 - Koetz, Joachim
T1 - Kinetically controlled growth of gold nanotriangles in a vesicular template phase by adding a strongly alternating polyampholyte
JF - Journal of dispersion science and technology
N2 - This paper is focused on the temperature-dependent synthesis of gold nanotriangles in a vesicular template phase, containing phosphatidylcholine and AOT, by adding the strongly alternating polyampholyte PalPhBisCarb.
UV-vis absorption spectra in combination with TEM micrographs show that flat gold nanoplatelets are formed predominantly in the presence of the polyampholyte at 45°C. The formation of triangular and hexagonal nanoplatelets can be directly influenced by the kinetic approach, i.e., by varying the polyampholyte dosage rate at 45°C. Corresponding zeta potential measurements indicate that a temperature-dependent adsorption of the polyampholyte on the {111} faces will induce the symmetry breaking effect, which is responsible for the kinetically controlled hindered vertical and preferred lateral growth of the nanoplatelets.
KW - Kinetically controlled nanocrystal growth
KW - nanotriangles
KW - polyampholytes
Y1 - 2016
U6 - https://doi.org/10.1080/01932691.2016.1220318
SN - 0193-2691
SN - 1532-2351
VL - 38
IS - 8
SP - 1073
EP - 1078
PB - Taylor & Francis
CY - Philadelphia
ER -
TY - THES
A1 - Margraf, Johannes T.
T1 - Science-driven chemical machine learning
Y1 - 2023
ER -
TY - JOUR
A1 - Deng, Zijun
A1 - Wang, Weiwei
A1 - Xu, Xun
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - Polydopamine-based biofunctional substrate coating promotes mesenchymal stem cell migration
JF - MRS advances : a journal of the Materials Research Society (MRS)
N2 - Rapid migration of mesenchymal stem cells (MSCs) on device surfaces could support in vivo tissue integration and might facilitate in vitro organoid formation. Here, polydopamine (PDA) is explored as a biofunctional coating to effectively promote MSC motility. It is hypothesized that PDA stimulates fibronectin deposition and in this way enhances integrin-mediated migration capability. The random and directional cell migration was investigated by time-lapse microscopy and gap closure assay respectively, and analysed with softwares as computational tools. A higher amount of deposited fibronectin was observed on PDA substrate, compared to the non-coated substrate. The integrin beta 1 activation and focal adhesion kinase (FAK) phosphorylation at Y397 were enhanced on PDA substrate, but the F-actin cytoskeleton was not altered, suggesting MSC migration on PDA was regulated by integrin initiated FAK signalling. This study strengthens the biofunctionality of PDA coating for regulating stem cells and offering a way of facilitating tissue integration of devices.
Y1 - 2021
U6 - https://doi.org/10.1557/s43580-021-00091-4
SN - 2059-8521
VL - 6
IS - 31
SP - 739
EP - 744
PB - Springer Nature Switzerland AG
CY - Cham
ER -
TY - JOUR
A1 - Machatschek, Rainhard Gabriel
A1 - Saretia, Shivam
A1 - Lendlein, Andreas
T1 - Assessing the influence of temperature-memory creation on the degradation of copolyesterurethanes in ultrathin films
JF - Advanced materials interfaces
N2 - Copolyesterurethanes (PDLCLs) based on oligo(epsilon-caprolactone) (OCL) and oligo(omega-pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature-memory polymers. The temperature-memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt% OPDL content are carried out under enzymatic catalysis. The temperature-memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization-modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X-ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation.
KW - block copolymers
KW - degradation
KW - Langmuir monolayers
KW - rheology
KW - temperature-memory polymers
Y1 - 2021
U6 - https://doi.org/10.1002/admi.202001926
SN - 2196-7350
VL - 8
IS - 6
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Sperlich, Eric
A1 - Köckerling, Martin
T1 - The double cluster compound [Nb6Cl14(MeCN)(4)] [Nb6Cl14(pyz)(4)].6MeCN (Me: methyl, pyz: pyrazine) with a layered structure resulting from weak intermolecular interactions
JF - Zeitschrift für Naturforschung
N2 - The synthesis and the crystal structure of the double cluster compound [Nb6Cl14(MeCN)(4)][Nb6Cl14(pyz)(4)]middot6CH(3)CN are described. The synthesis is based on a partial ligand exchange reaction, which proceeds upon dissolving [Nb6Cl14(pyz)(4)]middot2CH(2)Cl(2) in acetonitrile. The compound is built up of two discrete neutral cluster units, which consist of octahedra of Nb-6 atoms coordinated by 12 edge-bridging chlorido and two terminal chlorido ligands, and four acetonitrile ligands on one and four pyrazine ligands on the other cluster unit. Co-crystallized acetonitrile molecules are also present. The single-crystal structure determination has revealed a cluster arrangement in which the [Nb6Cl14(pyz)(4)] units are connected by (halogen) lone-pair-(pyrazine) pi interactions. These lead to chains of [Nb6Cl14(pyz)(4)] clusters. These chains are further connected to cluster layers by (nitrile-halogen) dipole-dipole interactions, in which the [Nb6Cl14(MeCN)(4)] and co-crystallized MeCN molecules are also involved. These cluster layers are arranged parallel to the crystallographic {011} plane.
KW - cluster
KW - crystal structure
KW - dipole-dipole interaction
KW - halide
KW - lone-pair-pi interactions
KW - niobium
Y1 - 2023
U6 - https://doi.org/10.1515/znb-2023-0001
SN - 0932-0776
SN - 1865-7117
VL - 78
IS - 5
SP - 279
EP - 283
PB - De Gruyter
CY - Berlin
ER -
TY - JOUR
A1 - Kreuzer, Lucas
A1 - Widmann, Tobias
A1 - Geiger, Christina
A1 - Wang, Peixi
A1 - Vagias, Apostolos N.
A1 - Heger, Julian Eliah
A1 - Haese, Martin
A1 - Hildebrand, Viet
A1 - Laschewsky, André
A1 - Papadakis, Christine M.
A1 - Müller-Buschbaum, Peter
T1 - Salt-dependent phase transition behavior of doubly thermoresponsive poly(sulfobetaine)-based diblock copolymer thin films
JF - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society
N2 - The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely, poly(4-(N-(3'-methacrylamidopropyl)-N, N-dimethylammonio) butane-1-sulfonate) (PSBP), showing an upper critical solution temperature, and a nonionic block, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), exhibiting a lower critical solution temperature. The swelling kinetics in D2O vapor at 15 degrees C and the phase transition kinetics upon heating the swollen film to 60 degrees C and cooling back to 15 degrees C are followed with simultaneous time-of-flight neutron reflectometry and spectral reflectance measurements. These are complemented by Fourier transform infrared spectroscopy. The collapse temperature of PNIPMAM and the swelling temperature of PSBP are found at lower temperatures than in aqueous solution, which is attributed to the high polymer concentration in the thin-film geometry. Upon inclusion of sub-stoichiometric amounts (relative to the monomer units) of NaBr in the films, the water incorporation is significantly increased. This increase is mainly attributed to a salting-in effect on the zwitterionic PSBP block. Whereas the addition of NaBr notably shifts the swelling temperature of PSBP to lower temperatures, the collapse temperature of PNIPMAM remains unaffected by the presence of salt in the films.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.langmuir.1c01342
SN - 0743-7463
SN - 1520-5827
VL - 37
IS - 30
SP - 9179
EP - 9191
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Pessanha, Tatiana
A1 - Paschoalino, Waldemir J.
A1 - Deroco, Patricia B.
A1 - Kogikoski Junior, Sergio
A1 - Moraes, Ana C. M. de
A1 - Carvalho Castro de Silva, Cecilia de
A1 - Kubota, Lauro T.
T1 - Interfacial capacitance of graphene oxide films electrodes
BT - Fundamental studies on electrolytes interface aiming (bio)sensing applications
JF - Electroanalysis : an internatinal journal devoted to electroanalysis, sensors and bioelectronic devices
N2 - The understanding of bidimensional materials dynamics and its electrolyte interface equilibrium, such as graphene oxide (GO), is critical for the development of a capacitive biosensing platform. The interfacial capacitance (C-i) of graphene-based materials may be tuned by experimental conditions such as pH optimization and cation size playing key roles at the enhancement of their capacitive properties allowing their application as novel capacitive biosensors. Here we reported a systematic study of C-i of multilayer GO films in different aqueous electrolytes employing electrochemical impedance spectroscopy for the application in a capacitive detection system. We demonstrated that the presence of ionizable oxygen-containing functional groups within multilayer GO film favors the interactions and the accumulation of cations in the structure of the electrodes enhancing the GO C-i in aqueous solutions, where at pH 7.0 (the best condition) the C-i was 340 mu F mg(-1) at -0.01 V vs Ag/AgCl. We also established that the hydrated cation radius affects the mobility and interaction with GO functional groups and it plays a critical role in the Ci, as demonstrated in the presence of different cations Na+=640 mu F mg(-1), Li+=575 mu F mg(-1) and TMA(+)=477 mu F mg(-1). As a proof-of-concept, the capacitive behaviour of GO was explored as biosensing platform for standard streptavidin-biotin systems. For this system, the C-i varied linearly with the log of the concentration of the targeting analyte in the range from 10 pg mL(-1) to 100 ng mL(-1), showing the promising applicability of capacitive GO based sensors for label-free biosensing.
KW - Interfacial capacitance
KW - Graphene oxide
KW - Functional groups
KW - Electrochemical impedance
KW - Graphene derivates
Y1 - 2021
U6 - https://doi.org/10.1002/elan.202100220
SN - 1521-4109
SN - 1040-0397
VL - 34
IS - 4
SP - 692
EP - 700
PB - Wiley-VCH
CY - Weinheim
ER -
TY - THES
A1 - Savatieiev, Oleksandr
T1 - Carbon nitride semiconductors: properties and application as photocatalysts in organic synthesis
N2 - Graphitic carbon nitrides (g-CNs) are represented by melon-type g-CN, poly(heptazine imides) (PHIs), triazine-based g-CN and poly(triazine imide) with intercalated LiCl (PTI/Li+Cl‒). These materials are composed of sp2-hybridized carbon and nitrogen atoms; C:N ratio is close to 3:4; the building unit is 1,3,5-triazine or tri-s-triazine; the building units are interconnected covalently via sp2-hybridized nitrogen atoms or NH-moieties; the layers are assembled into a stack via weak van der Waals forces as in graphite. Due to medium band gap (~2.7 eV) g-CNs, such as melon-type g-CN and PHIs, are excited by photons with wavelength ≤ 460 nm. Since 2009 g-CNs have been actively studied as photocatalysts in evolution of hydrogen and oxygen – two half-reactions of full water splitting, by employing corresponding sacrificial agents. At the same time application of g-CNs as photocatalysts in organic synthesis has been remaining limited to few reactions only. Cumulative Habilitation summarizes research work conducted by the group ‘Innovative Heterogeneous Photocatalysis’ between 2017-2023 in the field of carbon nitride organic photocatalysis, which is led by Dr. Oleksandr Savatieiev.
g-CN photocatalysts activate molecules, i.e. generate their more reactive open-shell intermediates, via three modes: i) Photoinduced electron transfer (PET); ii) Excited state proton-coupled electron transfer (ES-PCET) or direct hydrogen atom transfer (dHAT); iii) Energy transfer (EnT). The scope of reactions that proceed via oxidative PET, i.e. one-electron oxidation of a substrate to the corresponding radical cation, are represented by synthesis of sulfonylchlorides from S-acetylthiophenols. The scope of reactions that proceed via reductive PET, i.e. one-electron reduction of a substrate to the corresponding radical anion, are represented by synthesis of γ,γ-dichloroketones from the enones and chloroform.
Due to abundance of sp2-hybridized nitrogen atoms in the structure of g-CN materials, they are able to cleave X-H bonds in organic molecules and store temporary hydrogen atom. ES-PCET or dHAT mode of organic molecules activation to the corresponding radicals is implemented for substrates featuring relatively acidic X-H bonds and those that are characterized by low bond dissociation energy, such as C-H bond next to the heteroelements. On the other hand, reductively quenched g-CN carrying hydrogen atom reduces a carbonyl compound to the ketyl radical via PCET that is thermodynamically more favorable pathway compared to the electron transfer. The scope of these reactions is represented by cyclodimerization of α,β-unsaturated ketones to cyclopentanoles.
g-CN excited state demonstrates complex dynamics with the initial formation of singlet excited state, which upon intersystem crossing produces triplet excited state that is characterized by the lifetime > 2 μs. Due to long lifetime, g-CN activate organic molecules via EnT. For example, g-CN sensitizes singlet oxygen, which is the key intermediate in the dehydrogenation of aldoximes to nitrileoxides. The transient nitrileoxide undergoes [3+2]-cycloaddition to nitriles and gives oxadiazoles-1,2,4.
PET, ES-PCET and EnT are fundamental phenomena that are applied beyond organic photocatalysis. Hybrid composite is formed by combining conductive polymers, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with potassium poly(heptazine imide) (K-PHI). Upon PET, K-PHI modulated population of polarons and therefore conductivity of PEDOT:PSS. The initial state of PEDOT:PSS is recovered upon material exposure to O2. K-PHI:PEDOT:PSS may be applied in O2 sensing.
In the presence of electron donors, such as tertiary amines and alcohols, and irradiation with light, K-PHI undergoes photocharging – the g-CN material accumulates electrons and charge-compensating cations. Such photocharged state is stable under anaerobic conditions for weeks, but at the same time it is a strong reductant. This feature allows decoupling in time light harvesting and energy storage in the form of electron-proton couples from utilization in organic synthesis. The photocharged state of K-PHI reduces nitrobenzene to aniline, and enables dimerization of α,β-unsaturated ketones to hexadienones in dark.
N2 - Graphitische Kohlenstoffnitride (g-CNs) werden durch g-CN vom Melonen-Typ, Poly(heptazinimide) (PHIs), g-CN auf Triazinbasis und Poly(triazinimid) mit interkaliertem LiCl (PTI/Li+Cl-) repräsentiert. Diese Materialien bestehen aus sp2-hybridisierten Kohlenstoff- und Stickstoffatomen; das C:N-Verhältnis liegt nahe bei 3:4; das Grundgerüst ist 1,3,5-Triazin oder Tri-s-Triazin; die Grundgerüste sind kovalent über sp2-hybridisierte Stickstoffatome oder NH-Moleküle miteinander verbunden; die Schichten werden über schwache van-der-Waals-Kräfte wie in Graphit zu einem Stapel zusammengefügt. Aufgrund der mittleren Bandlücke (~2,7 eV) werden g-CNs, wie z. B. g-CN vom Melonen-Typ und PHIs, durch Photonen mit einer Wellenlänge ≤ 460 nm angeregt. Seit 2009 werden g-CNs aktiv als Photokatalysatoren für die Entwicklung von Wasserstoff und Sauerstoff - zwei Halbreaktionen der vollständigen Wasserspaltung - untersucht, indem entsprechende Opferstoffe eingesetzt werden. Gleichzeitig ist die Anwendung von g-CNs als Photokatalysatoren in der organischen Synthese auf wenige Reaktionen beschränkt geblieben. Die kumulative Habilitation fasst die Forschungsarbeiten zusammen, die von der Gruppe "Innovative heterogene Photokatalyse" zwischen 2017 und 2023 auf dem Gebiet der organischen Photokatalyse mit Kohlenstoffnitrid durchgeführt wurden, die von Dr. Oleksandr Savatieiev geleitet wird.
g-CN-Photokatalysatoren aktivieren Moleküle, d. h. sie erzeugen ihre reaktiveren Zwischenprodukte mit offener Schale über drei Modi: i) photoinduzierter Elektronentransfer (PET); ii) protonengekoppelter Elektronentransfer im angeregten Zustand (ES-PCET) oder direkter Wasserstoffatomtransfer (dHAT); iii) Energietransfer (EnT). Der Bereich der Reaktionen, die über oxidativen PET ablaufen, d. h. die Ein-Elektronen-Oxidation eines Substrats zum entsprechenden Radikalkation, wird durch die Synthese von Sulfonylchloriden aus S-Acetylthiophenolen dargestellt. Der Bereich der Reaktionen, die über reduktive PET ablaufen, d. h. Reduktion eines Substrats mit einem Elektron zum entsprechenden radikalischen Anion, wird durch die Synthese von γ,γ-Dichloroketonen aus Enonen und Chloroform repräsentiert.
Aufgrund der zahlreichen sp2-hybridisierten Stickstoffatome in der Struktur der g-CN-Materialien können sie X-H-Bindungen in organischen Molekülen spalten und temporäre Wasserstoffatome speichern. Der ES-PCET- oder dHAT-Modus der Aktivierung organischer Moleküle zu den entsprechenden Radikalen wird bei Substraten mit relativ sauren X-H-Bindungen und solchen, die sich durch eine niedrige Bindungsdissoziationsenergie auszeichnen, wie z. B. die C-H-Bindung neben den Heteroelementen, durchgeführt. Andererseits reduziert reduktiv gequenchtes g-CN, das ein Wasserstoffatom trägt, eine Carbonylverbindung über PCET zum Ketylradikal, was im Vergleich zum Elektronentransfer der thermodynamisch günstigere Weg ist. Der Umfang dieser Reaktionen wird durch die Cyclodimerisierung von α,β-ungesättigten Ketonen zu Cyclopentanolen dargestellt.
Der angeregte Zustand von g-CN zeigt eine komplexe Dynamik mit der anfänglichen Bildung eines angeregten Singulett-Zustands, der beim Übergang zwischen den Systemen einen angeregten Triplett-Zustand erzeugt, der durch eine Lebensdauer von > 2 μs gekennzeichnet ist. Aufgrund der langen Lebensdauer aktivieren g-CN organische Moleküle über EnT. So sensibilisiert g-CN beispielsweise Singulett-Sauerstoff, der das wichtigste Zwischenprodukt bei der Dehydrierung von Aldoximen zu Nitriloxiden ist. Das transiente Nitriloxid unterliegt einer [3+2]-Cycloaddition zu Nitrilen und ergibt Oxadiazole-1,2,4.
PET, ES-PCET und EnT sind grundlegende Phänomene, die über die organische Photokatalyse hinaus Anwendung finden. Hybridkomposit wird durch die Kombination von leitfähigen Polymeren wie Poly(3,4-ethylendioxythiophen)polystyrolsulfonat (PEDOT:PSS) mit Kaliumpoly(heptazinimid) (K-PHI) gebildet. Nach PET modulierte K-PHI die Population der Polaronen und damit die Leitfähigkeit von PEDOT:PSS. Der Ausgangszustand von PEDOT:PSS wird wiederhergestellt, wenn das Material O2 ausgesetzt wird. K-PHI:PEDOT:PSS kann für die O2-Sensorik verwendet werden.
In Gegenwart von Elektronendonatoren, wie tertiären Aminen und Alkoholen, und bei Lichteinstrahlung wird K-PHI photogeladen - das g-CN-Material sammelt Elektronen und ladungsausgleichende Kationen an. Dieser photogeladene Zustand ist unter anaeroben Bedingungen wochenlang stabil, gleichzeitig ist er aber ein starkes Reduktionsmittel. Diese Eigenschaft ermöglicht die zeitliche Entkopplung von Lichtsammlung und Energiespeicherung in Form von Elektron-Protonen-Paaren von der Nutzung in der organischen Synthese. Der photogeladene Zustand von K-PHI reduziert Nitrobenzol zu Anilin und ermöglicht die Dimerisierung von α,β-ungesättigten Ketonen zu Hexadienonen im Dunkeln.
KW - carbon nitride
KW - photocatalysis
KW - photochemistry
KW - photocharging
KW - organic synthesis
Y1 - 2023
ER -
TY - JOUR
A1 - Wang, Peixi
A1 - Geiger, Christina
A1 - Kreuzer, Lucas
A1 - Widmann, Tobias
A1 - Reitenbach, Julija
A1 - Liang, Suzhe
A1 - Cubitt, Robert
A1 - Henschel, Cristiane
A1 - Laschewsky, André
A1 - Papadakis, Christine M.
A1 - Müller-Buschbaum, Peter
T1 - Poly(sulfobetaine)-based diblock copolymer thin films in water/acetone atmosphere: modulation of water hydration and co-nonsolvency-triggered film contraction
JF - Langmuir : the ACS journal of surfaces and colloids
N2 - The water swelling and subsequent solvent exchange including co-nonsolvency behavior of thin films of a doubly thermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, and Fourier transform infrared spectroscopy.
The DBC consists of a thermo-responsive zwitterionic (poly(4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate)) (PSBP) block, featuring an upper critical solution temperature transition in aqueous media but being insoluble in acetone, and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, featuring a lower critical solution temperature transition in water, while being soluble in acetone.
Homogeneous DBC films of 50-100 nm thickness are first swollen in saturated water vapor (H2OorD2O), before they are subjected to a contraction process by exposure to mixed saturated water/acetone vapor (H2OorD2O/acetone-d6 = 9:1 v/v).
The affinity of the DBC film toward H2O is stronger than for D2O, as inferred from the higher film thickness in the swollen state and the higher absorbed water content, thus revealing a pronounced isotope sensitivity.
During the co-solvent-induced switching by mixed water/acetone vapor, a two-step film contraction is observed, which is attributed to the delayed expulsion of water molecules and uptake of acetone molecules.
The swelling kinetics are compared for both mixed vapors (H2O/acetone-d6 and D2O/acetone-d6) and with those of the related homopolymer films.
Moreover, the concomitant variations of the local environment around the hydrophilic groups located in the PSBP and PNIPMAM blocks are followed.
The first contraction step turns out to be dominated by the behavior of the PSBP block, where as the second one is dominated by the PNIPMAM block.
The unusual swelling and contraction behavior of the latter block is attributed to its co-nonsolvency behavior.
Furthermore, we observe cooperative hydration effects in the DBC films, that is, both polymer blocks influence each other's solvation behavior.
Y1 - 2022
U6 - https://doi.org/10.1021/acs.langmuir.2c00451
SN - 0743-7463
SN - 1520-5827
VL - 38
IS - 22
SP - 6934
EP - 6948
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Kuntze, Kim
A1 - Viljakka, Jani
A1 - Titov, Evgenii
A1 - Ahmed, Zafar
A1 - Kalenius, Elina
A1 - Saalfrank, Peter
A1 - Priimagi, Arri
T1 - Towards low-energy-light-driven bistable photoswitches
BT - ortho-fluoroaminoazobenzenes
JF - Photochemical & photobiological sciences / European Society for Photobiology
N2 - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days.
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Y1 - 2022
U6 - https://doi.org/10.1007/s43630-021-00145-4
SN - 1474-905X
SN - 1474-9092
VL - 21
IS - 2
SP - 159
EP - 173
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Xie, Dongjiu
A1 - Xu, Yaolin
A1 - Wang, Yonglei
A1 - Pan, Xuefeng
A1 - Härk, Eneli
A1 - Kochovski, Zdravko
A1 - Eljarrat, Alberto
A1 - Müller, Johannes
A1 - Koch, Christoph T.
A1 - Yuan, Jiayin
A1 - Lu, Yan
T1 - Poly(ionic liquid) nanovesicle-templated carbon nanocapsules functionalized with uniform iron nitride nanoparticles as catalytic sulfur host for Li-S batteries
JF - ACS nano
N2 - Poly(ionic liquid)s (PIL) are common precursors for heteroatom-doped carbon materials. Despite a relatively higher carbonization yield, the PIL-to-carbon conversion process faces challenges in preserving morphological and structural motifs on the nanoscale. Assisted by a thin polydopamine coating route and ion exchange, imidazoliumbased PIL nanovesicles were successfully applied in morphology-maintaining carbonization to prepare carbon composite nanocapsules. Extending this strategy further to their composites, we demonstrate the synthesis of carbon composite nanocapsules functionalized with iron nitride nanoparticles of an ultrafine, uniform size of 3-5 nm (termed "FexN@C "). Due to its unique nanostructure, the sulfur-loaded FexN@C electrode was tested to efficiently mitigate the notorious shuttle effect of lithium polysulfides (LiPSs) in Li-S batteries. The cavity of the carbon nanocapsules was spotted to better the loading content of sulfur. The well-dispersed iron nitride nanoparticles effectively catalyze the conversion of LiPSs to Li2S, owing to their high electronic conductivity and strong binding power to LiPSs. Benefiting from this well-crafted composite nanostructure, the constructed FexN@C/S cathode demonstrated a fairly high discharge capacity of 1085 mAh g(-1) at 0.5 C initially, and a remaining value of 930 mAh g(-1 )after 200 cycles. In addition, it exhibits an excellent rate capability with a high initial discharge capacity of 889.8 mAh g(-1) at 2 C. This facile PIL-to-nanocarbon synthetic approach is applicable for the exquisite design of complex hybrid carbon nanostructures with potential use in electrochemical energy storage and conversion.
KW - poly(ionic liquid)s
KW - nanovesicles
KW - sulfur host
KW - iron nitride
KW - Li-S
KW - batteries
Y1 - 2022
U6 - https://doi.org/10.1021/acsnano.2c01992
SN - 1936-0851
SN - 1936-086X
VL - 16
IS - 7
SP - 10554
EP - 10565
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Neffe, Axel T.
A1 - Löwenberg, Candy
A1 - Julich-Gruner, Konstanze K.
A1 - Behl, Marc
A1 - Lendlein, Andreas
T1 - Thermally-induced shape-memory behavior of degradable gelatin-based networks
JF - International journal of molecular sciences
N2 - Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) alpha,omega-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27-23 kPa and Young's moduli of 215-360 kPa at 4 degrees C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 degrees C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R-r close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.
KW - shape-memory hydrogel
KW - active polymer
KW - biopolymer
KW - mechanical
KW - properties
KW - degradation
Y1 - 2021
U6 - https://doi.org/10.3390/ijms22115892
SN - 1422-0067
SN - 1661-6596
VL - 22
IS - 11
PB - Molecular Diversity Preservation International
CY - Basel
ER -
TY - JOUR
A1 - Bochove, Bas van
A1 - Grijpma, Dirk W.
A1 - Lendlein, Andreas
A1 - Seppälä, Jukka
T1 - Designing advanced functional polymers for medicine
JF - European polymer journal : EPJ
Y1 - 2021
U6 - https://doi.org/10.1016/j.eurpolymj.2021.110573
SN - 0014-3057
VL - 155
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Hwang, Jinyeon
A1 - Zhang, Wuyong
A1 - Youk, Sol
A1 - Schutjajew, Konstantin
A1 - Oschatz, Martin
T1 - Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials
JF - Energy technology : generation, conversion, storage, distribution
N2 - The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites.
KW - anodes
KW - hybrid materials
KW - nitrogen-doped carbon
KW - porous carbon
KW - lithium-ion capacitors
Y1 - 2021
U6 - https://doi.org/10.1002/ente.202001054
SN - 2194-4296
VL - 9
IS - 3
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Pan, Xuefeng
A1 - Sarhan, Radwan Mohamed
A1 - Kochovski, Zdravko
A1 - Chen, Guosong
A1 - Taubert, Andreas
A1 - Mei, Shilin
A1 - Lu, Yan
T1 - Template synthesis of dual-functional porous MoS2 nanoparticles with photothermal conversion and catalytic properties
JF - Nanoscale
N2 - Advanced catalysis triggered by photothermal conversion effects has aroused increasing interest due to its huge potential in environmental purification.
In this work, we developed a novel approach to the fast degradation of 4-nitrophenol (4-Nip) using porous MoS2 nanoparticles as catalysts, which integrate the intrinsic catalytic property of MoS2 with its photothermal conversion capability.
Using assembled polystyrene-b-poly(2-vinylpyridine) block copolymers as soft templates, various MoS 2 particles were prepared, which exhibited tailored morphologies (e.g., pomegranate-like, hollow, and open porous structures).
The photothermal conversion performance of these featured particles was compared under near-infrared (NIR) light irradiation.
Intriguingly, when these porous MoS2 particles were further employed as catalysts for the reduction of 4-Nip, the reaction rate constant was increased by a factor of 1.5 under NIR illumination.
We attribute this catalytic enhancement to the open porous architecture and light-to-heat conversion performance of the MoS2 particles. This contribution offers new opportunities for efficient photothermal-assisted catalysis.
Y1 - 2022
U6 - https://doi.org/10.1039/d2nr01040b
SN - 2040-3372
VL - 14
IS - 18
SP - 6888
EP - 6901
PB - RSC Publ. (Royal Society of Chemistry)
CY - Cambridge
ER -
TY - JOUR
A1 - Zhao, Yuhang
A1 - Sarhan, Radwan Mohamed
A1 - Eljarrat, Alberto
A1 - Kochovski, Zdravko
A1 - Koch, Christoph
A1 - Schmidt, Bernd
A1 - Koopman, Wouter-Willem Adriaan
A1 - Lu, Yan
T1 - Surface-functionalized Au-Pd nanorods with enhanced photothermal conversion and catalytic performance
JF - ACS applied materials & interfaces
N2 - Bimetallic nanostructures comprising plasmonic and catalytic components have recently emerged as a promising approach to generate a new type of photo-enhanced nanoreactors. Most designs however concentrate on plasmon-induced charge separation, leaving photo-generated heat as a side product.
This work presents a photoreactor based on Au-Pd nanorods with an optimized photothermal conversion, which aims to effectively utilize the photo-generated heat to increase the rate of Pd-catalyzed reactions. Dumbbell-shaped Au nanorods were fabricated via a seed-mediated growth method using binary surfactants. Pd clusters were selectively grown at the tips of the Au nanorods, using the zeta potential as a new synthetic parameter to indicate the surfactant remaining on the nanorod surface.
The photothermal conversion of the Au-Pd nanorods was improved with a thin layer of polydopamine (PDA) or TiO2.
As a result, a 60% higher temperature increment of the dispersion compared to that for bare Au rods at the same light intensity and particle density could be achieved.
The catalytic performance of the coated particles was then tested using the reduction of 4-nitrophenol as the model reaction. Under light, the PDA-coated Au-Pd nanorods exhibited an improved catalytic activity, increasing the reaction rate by a factor 3.
An analysis of the activation energy confirmed the photoheating effect to be the dominant mechanism accelerating the reaction. Thus, the increased photothermal heating is responsible for the reaction acceleration.
Interestingly, the same analysis shows a roughly 10% higher reaction rate for particles under illumination compared to under dark heating, possibly implying a crucial role of localized heat gradients at the particle surface.
Finally, the coating thickness was identified as an essential parameter determining the photothermal conversion efficiency and the reaction acceleration.
KW - Au-Pd nanorods
KW - PDA
KW - photothermal conversion
KW - surface plasmon
KW - 4-nitrophenol
Y1 - 2022
U6 - https://doi.org/10.1021/acsami.2c00221
SN - 1944-8244
SN - 1944-8252
VL - 14
IS - 15
SP - 17259
EP - 17272
PB - American Chemical Society
CY - Washington, DC
ER -
TY - JOUR
A1 - Floyd, Thomas G.
A1 - Song, Ji-Inn
A1 - Hapeshi, Alexia
A1 - Laroque, Sophie
A1 - Hartlieb, Matthias
A1 - Perrier, Sebastien
T1 - Bottlebrush copolymers for gene delivery: influence of architecture, charge density, and backbone length on transfection efficiency
JF - Journal of materials chemistry : B, materials for biology and medicine
N2 - The influence of polymer architecture of polycations on their ability to transfect mammalian cells is probed. Polymer bottle brushes with grafts made from partially hydrolysed poly(2-ethyl-2-oxazoline) are used while varying the length of the polymer backbone as well as the degree of hydrolysis (cationic charge content). Polyplex formation is investigated via gel electrophoresis, dye-displacement and dynamic light scattering. Bottle brushes show a superior ability to complex pDNA when compared to linear copolymers. Also, nucleic acid release was found to be improved by a graft architecture. Polyplexes based on bottle brush copolymers showed an elongated shape in transmission electron microscopy images. The cytotoxicity against mammalian cells is drastically reduced when a graft architecture is used instead of linear copolymers. Moreover, the best-performing bottle brush copolymer showed a transfection ability comparable with that of linear poly(ethylenimine), the gold standard of polymeric transfection agents, which is used as positive control. In combination with their markedly lowered cytotoxicity, cationic bottle brush copolymers are therefore shown to be a highly promising class of gene delivery vectors.
Y1 - 2022
U6 - https://doi.org/10.1039/d2tb00490a
SN - 2050-750X
SN - 2050-7518
VL - 10
IS - 19
SP - 3696
EP - 3704
PB - Royal Society of Chemistry
CY - London [u.a.]
ER -
TY - JOUR
A1 - Abbasi, Ali
A1 - Xu, Yaolin
A1 - Khezri, Ramin
A1 - Etesami, Mohammad
A1 - Lin, C.
A1 - Kheawhom, Soorathep
A1 - Lu, Yan
T1 - Advances in characteristics improvement of polymeric membranes/separators for zinc-air batteries
JF - Materials Today Sustainability
N2 - Zinc-air batteries (ZABs) are gaining popularity for a wide range of applications due to their high energy density, excellent safety, and environmental friendliness. A membrane/separator is a critical component of ZABs, with substantial implications for battery performance and stability, particularly in the case of a battery in solid state format, which has captured increased attention in recent years. In this review, recent advances as well as insight into the architecture of polymeric membrane/separators for ZABs including porous polymer separators (PPSs), gel polymer electrolytes (GPEs), solid polymer electrolytes (SPEs) and anion exchange membranes (AEMs) are discussed. The paper puts forward strategies to enhance stability, ionic conductivity, ionic selectivity, electrolyte storage capacity and mechanical properties for each type of polymeric membrane. In addition, the remaining major obstacles as well as the most potential avenues for future research are examined in detail.
KW - Ionic selectivity
KW - Ionic conductivity
KW - Gel polymer
KW - Ion exchange
KW - Porous
KW - polymer
Y1 - 2022
U6 - https://doi.org/10.1016/j.mtsust.2022.100126
SN - 2589-2347
VL - 18
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Mayer, Dennis
A1 - Picconi, David
A1 - Robinson, Matthew S.
A1 - Gühr, Markus
T1 - Experimental and theoretical gas-phase absorption spectra of thionated uracils
JF - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
N2 - We present a comparative study of the gas-phase UV spectra of uracil and its thionated counterparts (2-thiouracil, 4-thiouracil and 2,4-dithiouracil), closely supported by time-dependent density functional theory calculations to assign the transitions observed. We systematically discuss pure gas-phase spectra for the (thio)uracils in the range of 200-400 nm (similar to 3.2-6.4 eV), and examine the spectra of all four species with a single theoretical approach. We note that specific vibrational modelling is needed to accurately determine the spectra across the examined wavelength range, and systematically model the transitions that appear at wavelengths shorter than 250 nm. Additionally, we find in the cases of 2-thiouracil and 2,4-dithiouracil, that the gas-phase spectra deviate significantly from some previously published solution-phase spectra, especially those collected in basic environments.
KW - Thiouracil
KW - Uracil
KW - UV-VIS Spectroscopy
KW - Excited-state calculations;
KW - TD-DFT
KW - Gas phase
Y1 - 2022
U6 - https://doi.org/10.1016/j.chemphys.2022.111500
SN - 0301-0104
VL - 558
PB - Elsevier
CY - Amsterdam
ER -
TY - JOUR
A1 - Zimmermann, Marc
A1 - Stomps, Benjamin René Harald
A1 - Schulte-Osseili, Christine
A1 - Grigoriev, Dmitry
A1 - Ewen, Dirk
A1 - Morgan, Andrew
A1 - Böker, Alexander
T1 - Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn
JF - Textile Research Journal
N2 - Polypropylene as one of the world's top commodity polymers is also widely used in the textile industry. However, its non-polar nature and partially crystalline structure significantly complicate the process of industrial coloring of polypropylene. Currently, textiles made of polypropylene or with a significant proportion of polypropylene are dyed under quite harsh conditions, including the use of high pressures and temperatures, which makes this process energy intensive. This research presents a three-step synthesis of coloring agents, capable of adhering onto synthetic polypropylene yarns without harsh energy-consuming conditions. This is possible by encapsulation of organic pigments using trimethoxyphenylsilane, introduction of surface double bonds via modification of the silica shell with trimethoxysilylpropylmethacrylate and final attachment of highly adhesive anchor peptides using thiol-ene chemistry. We demonstrate the applicability of this approach by dyeing polypropylene yarns in a simple process under ambient conditions after giving a step-by-step guide for the synthesis of these new dyeing agents. Finally, the successful dyeing of the yarns is visualized, and its practicability is discussed.
KW - anchor peptides
KW - organic dye pigments
KW - coloring agents
KW - polypropylene
KW - yarns
Y1 - 2020
U6 - https://doi.org/10.1177/0040517520932231
SN - 0040-5175
SN - 1746-7748
VL - 91
IS - 1-2
SP - 28
EP - 39
PB - Sage Publ.
CY - London
ER -
TY - JOUR
A1 - Ilic, Ivan
A1 - Schutjajew, Konstantin
A1 - Zhang, Wuyong
A1 - Oschatz, Martin
T1 - Changes of porosity of hard carbons during mechanical treatment and the relevance for sodium-ion anodes
JF - Carbon : an international journal sponsored by the American Carbon Society
N2 - Lithium-ion batteries have revolutionized battery technology. However, the scarcity of lithium in nature is driving the search for alternatives. For that reason, sodium-ion batteries have attracted increasing attention in recent years. The main obstacle to their development is the anode as, unlike for lithium-ion batteries, graphite cannot be used due to the inability to form stoichiometrically useful intercalation compounds with sodium. A promising candidate for sodium storage is hard carbon a form of nongraphitisable carbon, that can be synthesized from various precursor materials. Processing of hard carbons is often done by using mechanochemical treatments. Although it is generally accepted and often observed that they can influence the porosity of hard carbons, their effect on battery performance not well understood. Here, the changes in porosity occurring during ball milling are elucidated and related to the properties of hard carbons in sodium storage. Analysis by combined gas physisorption and small angle X-ray scattering shows that porosity changes during ball milling with a significant increase of the open porosity, unsuitable for reversible sodium storage, and decrease of the closed porosity, suitable for reversible sodium storage. While pristine hard carbon can store 58.5 mAh g(-1) in the closed pores, upon 5 h of mechanical treatment in a ball mill it can only store 35.5 mAh g(-1). The obtained results are furthermore pointing towards the disputed "intercalation-adsorption" mechanism.
KW - Hard carbons
KW - Sodium-ion batteries
KW - Anodes
KW - Microporosity
KW - Ball milling
Y1 - 2022
U6 - https://doi.org/10.1016/j.carbon.2021.09.063
SN - 0008-6223
SN - 1873-3891
VL - 186
SP - 55
EP - 63
PB - Elsevier Science
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Gupta, Banshi D.
A1 - Pathak, Anisha
A1 - Shrivastav, Anand
T1 - Optical Biomedical Diagnostics Using Lab-on-Fiber Technology
BT - a review
JF - Photonics : open access journal
N2 - Point-of-care and in-vivo bio-diagnostic tools are the current need for the present critical scenarios in the healthcare industry. The past few decades have seen a surge in research activities related to solving the challenges associated with precise on-site bio-sensing. Cutting-edge fiber optic technology enables the interaction of light with functionalized fiber surfaces at remote locations to develop a novel, miniaturized and cost-effective lab on fiber technology for bio-sensing applications. The recent remarkable developments in the field of nanotechnology provide innumerable functionalization methodologies to develop selective bio-recognition elements for label free biosensors. These exceptional methods may be easily integrated with fiber surfaces to provide highly selective light-matter interaction depending on various transduction mechanisms. In the present review, an overview of optical fiber-based biosensors has been provided with focus on physical principles used, along with the functionalization protocols for the detection of various biological analytes to diagnose the disease. The design and performance of these biosensors in terms of operating range, selectivity, response time and limit of detection have been discussed. In the concluding remarks, the challenges associated with these biosensors and the improvement required to develop handheld devices to enable direct target detection have been highlighted.
KW - fiber optic sensors
KW - synthesis
KW - interferometry
KW - fluorescence
KW - SERS
KW - SPR
KW - immunosensors
KW - enzymatic sensors
KW - molecular imprinted polymers
Y1 - 2022
U6 - https://doi.org/10.3390/photonics9020086
SN - 2304-6732
VL - 9
IS - 2
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Akampurira, Denis
A1 - Akala, Hoseah M.
A1 - Derese, Solomon
A1 - Heydenreich, Matthias
A1 - Yenesew, Abiy
T1 - A new C-C linked benzophenathridine-2-quinoline dimer, and the antiplasmodial activity of alkaloids from Zanthoxylum holstzianum
JF - Natural product research
N2 - The CH2Cl2/MeOH (1:1) extract of Zanthoxylum holstzianum stem bark showed good antiplasmodial activity (IC50 2.5 +/- 0.3 and 2.6 +/- 0.3 mu g/mL against the W2 and D6 strains of Plasmodium falciparum, respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (1), nitidine (2), dihydrochelerythine (3), norchelerythrine (5), arnottianamide (8)]; a 2-quinolone alkaloid [N-methylflindersine (4)]; a lignan [4,4 '-dihydroxy-3,3 '-dimethoxylignan-9,9 '-diyl diacetate (7)] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline (6)] were isolated. The CH2Cl2/MeOH (1:1) extract of the root bark afforded 1, 3-6, 8, chelerythridimerine (9) and 9-demethyloxychelerythrine (10). Holstzianoquinoline (6) is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds (1-5) tested against two strains of P. falciparum, nitidine (IC50 0.11 +/- 0.01 mu g/mL against W2 and D6 strains) and norchelerythrine (IC50 value of 0.15 +/- 0.01 mu g/mL against D6 strain) were the most active.
KW - Antiplasmodial
KW - benzophenanthridine alkaloid
KW - holstzianoquinoline;
KW - rutaceae
KW - Zanthoxylum holstzianum
Y1 - 2022
U6 - https://doi.org/10.1080/14786419.2022.2034810
SN - 1478-6419
SN - 1478-6427
VL - 37
IS - 13
SP - 2161
EP - 2171
PB - Taylor & Francis
CY - London [u.a.]
ER -
TY - JOUR
A1 - Kreuzer, Lucas
A1 - Lindenmeir, Christoph
A1 - Geiger, Christina
A1 - Widmann, Tobias
A1 - Hildebrand, Viet
A1 - Laschewsky, André
A1 - Papadakis, Christine M.
A1 - Müller-Buschbaum, Peter
T1 - Poly(sulfobetaine) versus poly(N-isopropylmethacrylamide)
BT - co-nonsolvency-type behavior of thin films in a water/methanol atmosphere
JF - Macromolecules : a publication of the American Chemical Society
N2 - The swelling and co-nonsolvency behaviors in pure H2O and in a mixed H2O/CH3OH vapor atmosphere of two different polar, water-soluble polymers in thin film geometry are studied in situ. Films of a zwitterionic poly(sulfobetaine), namely, poly[3-((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a polar nonionic polymer, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), are investigated in real time by spectral reflectance (SR) measurements and Fourier transform infrared (FTIR) spectroscopy. Whereas PSPE is insoluble in methanol, PNIPMAM is soluble but exhibits cononsolvency behavior in water/methanol mixtures. First, the swelling of PSPE and PNIPMAM thin films in H2O vapor is followed. Subsequently, CH3OH is added to the vapor atmosphere, and its contracting effect on the water-swollen films is monitored, revealing a co-nonsolvency-type behavior for PNIPMAM and PSPE. SR measurements indicate that PSPE and PNIPMAM behave significantly different during the H2O swelling and subsequent exposure to CH3OH, not only with respect to the amounts of absorbed water and CH3OH, but also to the cosolvent-induced contraction mechanisms. While PSPE thin films exhibit an abrupt one-step contraction, the contraction of PNIPMAM thin films occurs in two steps. FTIR studies corroborate these findings on a molecular scale and reveal the role of the specific functional groups, both during the swelling and the cosolvent-induced switching of the solvation state.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.macromol.0c02281
SN - 0024-9297
SN - 1520-5835
VL - 54
IS - 3
SP - 1548
EP - 1556
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Deng, Zijun
A1 - Wang, Weiwei
A1 - Xua, Xun
A1 - Gould, Oliver E. C.
A1 - Kratz, Karl
A1 - Ma, Nan
A1 - Lendlein, Andreas
T1 - Polymeric sheet actuators with programmable bioinstructivity
JF - PNAS
N2 - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
KW - reversible shape-memory actuator
KW - mesenchymal stem cells
KW - calcium influx
KW - HDAC1
KW - RUNX2
Y1 - 2020
U6 - https://doi.org/10.1073/pnas.1910668117
SN - 1091-6490
VL - 117
IS - 4
SP - 1895
EP - 1901
PB - National Academy of Sciences
CY - Washington, DC
ER -
TY - JOUR
A1 - Saretia, Shivam
A1 - Machatschek, Rainhard Gabriel
A1 - Lendlein, Andreas
T1 - Degradation kinetics of oligo(ε-caprolactone) ultrathin films
BT - Influence of crystallinity
JF - MRS advances : a journal of the Materials Research Society (MRS)
N2 - The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(epsilon-caprolactone) (OCL) are prepared at the air-water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH similar to 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices.
Y1 - 2021
U6 - https://doi.org/10.1557/s43580-021-00067-4
SN - 2059-8521
VL - 6
IS - 33
SP - 790
EP - 795
PB - Springer Nature Switzerland AG
CY - Cham
ER -
TY - JOUR
A1 - Yue, Yanhua
A1 - Melani, Giacomo
A1 - Kirsch, Harald
A1 - Paarmann, Alexander
A1 - Saalfrank, Peter
A1 - Campen, Richard Kramer
A1 - Tong, Yujin
T1 - Structure and Reactivity of a-Al2O3(0001) Surfaces: How Do Al-I and Gibbsite-like Terminations Interconvert?
JF - The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis
N2 - The alpha-Al2O3(0001) surface has been extensively studied because of its significance in both fundamental research and application. Prior work suggests that in ultra-high-vacuum (UHV), in the absence of water, the so-called Al-I termination is thermodynamically favored, while in ambient, in contact with liquid water, a Gibbsite-like layer is created. While the view of the alpha- Al2O3(0001)/H2O(l) interface appears relatively clear in theory, experimental characterization of this system has resulted in estimates of surface acidity, i.e., isoelectric points, that differ by 4 pH units and surface structure that in some reports has non-hydrogen-bonded surface aluminol (Al-OH) groups and in others does not. In this study, we employed vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation to study the surface phonon modes of the differently terminated alpha-Al2O3(0001) surfaces in both UHV and ambient. We find that, on either water dosing of the Al-I in UHV or heat-induced dehydroxylation of the Gibbsite-like in ambient, the surfaces do not interconvert. This observation offers a new explanation for disagreements in prior work on the alpha-Al2O3(0001)/liquid water interface -different preparation methods may create surfaces that do not interconvert-and shows that the surface phonon spectral response offers a novel probe of interfacial hydrogen bonding structure.
Y1 - 2022
U6 - https://doi.org/10.1021/acs.jpcc.2c03743
SN - 1932-7447
SN - 1932-7455
VL - 126
IS - 31
SP - 13467
EP - 13476
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Tarazona Lizcano, Natalia Andrea
A1 - Machatschek, Rainhard Gabriel
A1 - Balcucho, Jennifer
A1 - Castro-Mayorga, Jinneth Lorena
A1 - Saldarriaga, Juan Francisco
A1 - Lendlein, Andreas
T1 - Opportunities and challenges for integrating the development of sustainable polymer materials within an international circular (bio)economy concept
JF - MRS energy & sustainability : science & technology & socio-economics & policy
N2 - The production and consumption of commodity polymers have been an indispensable part of the development of our modern society. Owing to their adjustable properties and variety of functions, polymer-based materials will continue playing important roles in achieving the Sustainable Development Goals (SDG)s, defined by the United Nations, in key areas such as healthcare, transport, food preservation, construction, electronics, and water management. Considering the serious environmental crisis, generated by increasing consumption of plastics, leading-edge polymers need to incorporate two types of functions: Those that directly arise from the demands of the application (e.g. selective gas and liquid permeation, actuation or charge transport) and those that enable minimization of environmental harm, e.g., through prolongation of the functional lifetime, minimization of material usage, or through predictable disintegration into non-toxic fragments. Here, we give examples of how the incorporation of a thoughtful combination of properties/functions can enhance the sustainability of plastics ranging from material design to waste management. We focus on tools to measure and reduce the negative impacts of plastics on the environment throughout their life cycle, the use of renewable sources for their synthesis, the design of biodegradable and/or recyclable materials, and the use of biotechnological strategies for enzymatic recycling of plastics that fits into a circular bioeconomy. Finally, we discuss future applications for sustainable plastics with the aim to achieve the SDGs through international cooperation.
Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities.
KW - biomaterial
KW - degradable
KW - functional
KW - life cycle assessment
KW - renewable
KW - sustainability
Y1 - 2022
U6 - https://doi.org/10.1557/s43581-021-00015-7
SN - 2329-2229
SN - 2329-2237
VL - 9
IS - 1
SP - 28
EP - 34
PB - Springer Nature
CY - London
ER -
TY - JOUR
A1 - Folikumah, Makafui Y.
A1 - Behl, Marc
A1 - Lendlein, Andreas
T1 - Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols
JF - MRS communications / a publication of the Materials Research Society
N2 - Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an alpha,omega-dithiol crosslinker in situ in a 'pseudo intramolecular' TTE. Competitive intermolecular TTE of TDP with externally added "basic" thiols increased the crosslinker concentration whilst "acidic" thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications.
KW - Biomaterials
KW - Biomimetic
KW - Mass spectrometry
KW - Nuclear magnetic resonance
KW - (NMR)
Y1 - 2021
U6 - https://doi.org/10.1557/s43579-021-00041-z
SN - 2159-6859
SN - 2159-6867
VL - 11
IS - 4
SP - 402
EP - 410
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Kleinpeter, Erich
A1 - Heydenreich, Matthias
A1 - Shainyan, Bagrat A.
T1 - At the experimental limit of the NMR conformational analysis
BT - Si-29 and C-13 NMR study of the conformational equilibrium of 1-phenyl-1-tert-butylsilacyclohexane
JF - Organic letters
N2 - The low temperature (95 K) NMR study of 1-Ph-1-t-Bu-silacyclohexane (1) showed the conformational equilibrium to be extremely one-sided toward thePh(ax),t-Bueq conformer. The barrier to interconversion has been measured (4.2-4.6 kcal/mol) and the conformational equilibrium [Delta nu = 1990.64 ppm (Si-29), 618.9 ppm (C-13), 1-Ph-ax:1-Pheq = (95.6-96.6%):(3.4-4.4%), K = 25 +/- 3, Delta G degrees = -RT ln K = 0.58-0.63 kcal/mol] analyzed. The assignment and quantification of the NMR signals is supported by MP2 and DFT calculations.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.orglett.0c03878
SN - 1523-7060
SN - 1523-7052
VL - 23
IS - 2
SP - 405
EP - 409
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Mullan, Thomas
A1 - Maschio, Lorenzo
A1 - Saalfrank, Peter
A1 - Usvyat, Denis
T1 - Reaction barriers on non-conducting surfaces beyond periodic local MP2
BT - Diffusion of hydrogen on alpha-Al2O3 (0001) as a test case
JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2 - The quest for "chemical accuracy" is becoming more and more demanded in the field of structure and kinetics of molecules at solid surfaces. In this paper, as an example, we focus on the barrier for hydrogen diffusion on a alpha-Al2O3 (0001) surface, aiming for a couple cluster singles, doubles, and perturbative triples [CCSD(T)]-level benchmark. We employ the density functional theory (DFT) optimized minimum and transition state structures reported by Heiden, Usvyat, and Saalfrank [J. Phys. Chem. C 123, 6675 (2019)]. The barrier is first evaluated at the periodic Hartree-Fock and local Moller-Plesset second-order perturbation (MP2) level of theory. The possible sources of errors are then analyzed, which includes basis set incompleteness error, frozen core, density fitting, local approximation errors, as well as the MP2 method error. Using periodic and embedded fragment models, corrections to these errors are evaluated. In particular, two corrections are found to be non-negligible (both from the chemical accuracy perspective and at the scale of the barrier value of 0.72 eV): the correction to the frozen core-approximation of 0.06 eV and the CCSD(T) correction of 0.07 eV. Our correlated wave function results are compared to barriers obtained from DFT. Among the tested DFT functionals, the best performing for this barrier is B3LYP-D3.
Y1 - 2022
U6 - https://doi.org/10.1063/5.0082805
SN - 0021-9606
SN - 1089-7690
VL - 156
IS - 7
PB - AIP Publishing
CY - Melville
ER -
TY - JOUR
A1 - Mawire, Phillip
A1 - Mozirandi, Winnie
A1 - Heydenreich, Matthias
A1 - Chi, Godloves Fru
A1 - Mukanganyama, Stanley
T1 - Isolation and antimicrobial activities of phytochemicals from Parinari curatellifolia (Chrysobalanaceae)
JF - Advances in pharmacological and pharmaceutical sciences
N2 - The widespread use of antimicrobial agents to treat infectious diseases has led to the emergence of antibiotic resistant pathogens. Plants have played a central role in combating many ailments in humans, and Parinari curatellifolia has been used for medicinal purposes. Seven extracts from P. curatellifolia leaves were prepared using serial exhaustive extraction of nonpolar to polar solvents. The microbroth dilution method was used to evaluate antimicrobial bioactivities of extracts. Five of the extracts were significantly active against at least one test microbe. Mycobacterium smegmatis was the most susceptible to most extracts. The methanol and ethanol extracts were the most active against M. smegmatis with an MIC of 25 mu g/mL. The hexane extract was the most active against Candida krusei with an MIC of 25 mu g/mL. None of the extracts significantly inhibited growth of Klebsiella pneumoniae and Staphylococcus aureus. Active extracts were selected for fractionation and isolation of pure compounds using gradient elution column chromatography. TLC analyses was carried out for pooling fractions of similar profiles. A total of 43 pools were obtained from 428 fractions. Pools 7 and 10 were selected for further isolation of single compounds. Four compounds, Pc4963r, Pc4962w, Pc6978p, and Pc6978o, were isolated. Evaluation of antimicrobial activities of Pc4963r, Pc4962w, and Pc6978p showed that the compounds were most active against C. krusei with MFC values ranging from 50 to 100 mu g/mL. Only Pc6978p was shown to be pure. Using spectroscopic analyses, the structure of Pc6978p was determined to be beta-sitosterol. The antifungal effects of beta-sitosterol were evaluated against C. krusei in vitro and on fabrics. Results showed that beta-sitosterol reduced the growth of C. krusei attached to Mendy fabric by 83%. Therefore, P. curatellifolia can be a source of lead compounds for prospective development of novel antimicrobial agents. Further work needs to be done to improve the antifungal activity of the isolated compound using quantitative structure-activity relationships.
Y1 - 2021
U6 - https://doi.org/10.1155/2021/8842629
SN - 2633-4682
SN - 2633-4690
PB - Hindawi
CY - London
ER -
TY - JOUR
A1 - Bekir, Marek
A1 - Jelken, Joachim
A1 - Jung, Se-Hyeong
A1 - Pich, Andrij
A1 - Pacholski, Claudia
A1 - Kopyshev, Alexey
A1 - Santer, Svetlana
T1 - Dual responsiveness of microgels induced by single light stimulus
JF - Applied physics letters
N2 - We report on the multiple response of microgels triggered by a single optical stimulus. Under irradiation, the volume of the microgels is reversibly switched by more than 20 times. The irradiation initiates two different processes: photo-isomerization of the photo-sensitive surfactant, which forms a complex with the anionic microgel, rendering it photo-responsive; and local heating due to a thermo-plasmonic effect within the structured gold layer on which the microgel is deposited. The photo-responsivity is related to the reversible accommodation/release of the photo-sensitive surfactant depending on its photo-isomerization state, while the thermo-sensitivity is intrinsically built in. We show that under exposure to green light, the thermo-plasmonic effect generates a local hot spot in the gold layer, resulting in the shrinkage of the microgel. This process competes with the simultaneous photo-induced swelling. Depending on the position of the laser spot, the spatiotemporal control of reversible particle shrinking/swelling with a predefined extent on a per-second base can be implemented.
Y1 - 2021
U6 - https://doi.org/10.1063/5.0036376
SN - 0003-6951
SN - 1077-3118
VL - 118
IS - 9
PB - American Institute of Physics
CY - Melville
ER -
TY - JOUR
A1 - Hoffmann, Falk
A1 - Machatschek, Rainhard Gabriel
A1 - Lendlein, Andreas
T1 - Analytical model and Monte Carlo simulations of polymer degradation with improved chain cut statistics
JF - Journal of materials research : JMR
N2 - The degradation of polymers is described by mathematical models based on bond cleavage statistics including the decreasing probability of chain cuts with decreasing average chain length. We derive equations for the degradation of chains under a random chain cut and a chain end cut mechanism, which are compared to existing models. The results are used to predict the influence of internal molecular parameters. It is shown that both chain cut mechanisms lead to a similar shape of the mass or molecular mass loss curve. A characteristic time is derived, which can be used to extract the maximum length of soluble fragments l of the polymer. We show that the complete description is needed to extract the degradation rate constant k from the molecular mass loss curve and that l can be used to design polymers that lose less mechanical stability before entering the mass loss phase.
KW - Modeling
KW - Degradable
KW - Polymer
KW - Molecular weight
KW - Simulation
Y1 - 2022
U6 - https://doi.org/10.1557/s43578-022-00495-4
SN - 0884-2914
SN - 2044-5326
VL - 37
IS - 5
SP - 1093
EP - 1101
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Neffe, Axel T.
A1 - Löwenberg, Candy
A1 - Lendlein, Andreas
T1 - Hydrogel networks by aliphatic dithiol Michael addition to glycidylmethacrylated gelatin
JF - MRS advances : a journal of the Materials Research Society (MRS)
N2 - Functionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by H-1 NMR and FT-IR spectroscopy. Hydrogel swelling (460-1900 vol%) and mechanical properties (Young's modulus E = 59-512 kPa, elongation at break epsilon(b) = 44-127%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 degrees C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation.
Y1 - 2021
U6 - https://doi.org/10.1557/s43580-021-00136-8
SN - 2059-8521
VL - 6
IS - 33
SP - 796
EP - 800
PB - Springer Nature Switzerland AG
CY - Cham
ER -
TY - JOUR
A1 - Lau, Skadi
A1 - Maier, Anna
A1 - Braune, Steffen
A1 - Gossen, Manfred
A1 - Lendlein, Andreas
T1 - Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials
JF - International journal of molecular sciences
N2 - Near-physiological in vitro thrombogenicity test systems for the evaluation of blood-contacting endothelialized biomaterials requires co-cultivation with platelets (PLT). However, the addition of PLT has led to unphysiological endothelial cell (EC) detachment in such in vitro systems. A possible cause for this phenomenon may be PLT activation triggered by the applied endothelial cell medium, which typically consists of basal medium (BM) and nine different supplements. To verify this hypothesis, the influence of BM and its supplements was systematically analyzed regarding PLT responses. For this, human platelet rich plasma (PRP) was mixed with BM, BM containing one of nine supplements, or with BM containing all supplements together. PLT adherence analysis was carried out in six-channel slides with plasma-treated cyclic olefin copolymer (COC) and poly(tetrafluoro ethylene) (PTFE, as a positive control) substrates as part of the six-channel slides in the absence of EC and under static conditions. PLT activation and aggregation were analyzed using light transmission aggregometry and flow cytometry (CD62P). Medium supplements had no effect on PLT activation and aggregation. In contrast, supplements differentially affected PLT adherence, however, in a polymer- and donor-dependent manner. Thus, the use of standard endothelial growth medium (BM + all supplements) maintains functionality of PLT under EC compatible conditions without masking the differences of PLT adherence on different polymeric substrates. These findings are important prerequisites for the establishment of a near-physiological in vitro thrombogenicity test system assessing polymer-based cardiovascular implant materials in contact with EC and PLT.
KW - cyclic olefin copolymer
KW - poly(tetrafluoroethylene)
KW - endothelial cells
KW - platelets
KW - in vitro thrombogenicity testing
Y1 - 2021
U6 - https://doi.org/10.3390/ijms22137006
SN - 1422-0067
SN - 1661-6596
VL - 22
IS - 13
PB - Molecular Diversity Preservation International
CY - Basel
ER -
TY - JOUR
A1 - Schönemann, Eric
A1 - Koc, Julian
A1 - Karthäuser, Jana
A1 - Özcan, Onur
A1 - Schanzenbach, Dirk
A1 - Schardt, Lisa
A1 - Rosenhahn, Axel
A1 - Laschewsky, André
T1 - Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties
JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2 - Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.biomac.0c01705
SN - 1525-7797
SN - 1526-4602
VL - 22
IS - 4
SP - 1494
EP - 1508
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Ihlenburg, Ramona
A1 - Mai, Tobias
A1 - Thünemann, Andreas F.
A1 - Baerenwald, Ruth
A1 - Saalwächter, Kay
A1 - Koetz, Joachim
A1 - Taubert, Andreas
T1 - Sulfobetaine hydrogels with a complex multilength-scale hierarchical structure
JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2 - Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N',N'-tetramethyl-N,N'-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers.
KW - Defects
KW - Hydrogels
KW - Nuclear magnetic resonance spectroscopy
KW - Scattering
KW - X-ray scattering
Y1 - 2021
U6 - https://doi.org/10.1021/acs.jpcb.0c10601
SN - 1520-6106
SN - 1520-5207
VL - 125
IS - 13
SP - 3398
EP - 3408
PB - American Chemical Society
CY - Washington
ER -
TY - JOUR
A1 - Lau, Skadi
A1 - Gossen, Manfred
A1 - Lendlein, Andreas
A1 - Jung, Friedrich
T1 - Differential sensitivity of assays for determining vein endothelial cell senescence
JF - Clinical hemorheology and microcirculation : blood flow and vessels
N2 - In vivo endothelialization of polymer-based cardiovascular implant materials is a promising strategy to reduce the risk of platelet adherence and the subsequent thrombus formation and implant failure. However, endothelial cells from elderly patients are likely to exhibit a senescent phenotype that may counteract endothelialization. The senescence status of cells should therefore be investigated prior to implantation of devices designed to be integrated in the blood vessel wall. Here, human umbilical vein endothelial cells (HUVEC) were cultivated up to passage (P) 4, 10 and 26/27 to determine the population doubling time and the senescence status by four different methods. Determination of the senescence-associated beta-galactosidase activity (SA-beta-Gal) was carried out by colorimetric staining and microscopy (i), as well as by photometric quantification (ii), and the expression of senescence-associated nuclear proteins p16 and p21 as well as the proliferation marker Ki67 was assessed by immunostaining (iii), and by flow cytometry (iv). The population doubling time of P27-cells was remarkably greater (103 +/- 65 h) compared to P4-cells (24 +/- 3 h) and P10-cell (37 +/- 15 h). Among the four different methods tested, the photometric SA-beta-Gal activity assay and the flow cytometric determination of p16 and Ki67 were most effective in discriminating P27-cells from P4- and P10-cells. These methods combined with functional endothelial cell analyses might aid predictions on the performance of implant endothelialization in vivo.
KW - Ageing
KW - population doubling time
KW - senescence-associated
KW - beta-galactosidase
KW - cell cycle inhibitors
KW - p16
KW - p21
KW - Ki67
Y1 - 2022
U6 - https://doi.org/10.3233/CH-211294
SN - 1386-0291
SN - 1875-8622
VL - 81
IS - 3
SP - 191
EP - 203
PB - IOS Press
CY - Amsterdam
ER -
TY - JOUR
A1 - Zhang, Pengfei
A1 - Rešetič, Andraž
A1 - Behl, Marc
A1 - Lendlein, Andreas
T1 - Multifunctionality in polymer networks by dynamic of coordination bonds
JF - Macromolecular chemistry and physics
N2 - The need for multifunctional materials is driven by emerging technologies and innovations, such as in the field of soft robotics and tactile or haptic systems, where minimizing the number of operational components is not only desirable, but can also be essential for realizing such devices. This study report on designing a multifunctional soft polymer material that can address a number of operating requirements such as solvent resistance, reshaping ability, self-healing capability, fluorescence stimuli-responsivity, and anisotropic structural functions. The numerous functional abilities are associated to rhodium(I)-phosphine coordination bonds, which in a polymer network act with their dynamic and non-covalently bonded nature as multifunctional crosslinks. Reversible aggregation of coordination bonds leads to changes in fluorescence emission intensity that responds to chemical or mechanical stimuli. The fast dynamics and diffusion of rhodium-phosphine ions across and through contacting areas of the material provide for reshaping and self-healing abilities that can be further exploited for assembly of multiple pieces into complex forms, all without any loss to material-sensing capabilities.
KW - assembly capabilities
KW - fluorescence stimuli‐ responsivity
KW - multiple functions
KW - reshaping abilities
KW - rhodium(I)– phosphine
KW - coordination bonds
KW - solvent resistance
Y1 - 2021
U6 - https://doi.org/10.1002/macp.202000394
SN - 1521-3935
VL - 222
IS - 3
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Göttlich, Richard
A1 - Graulich, Nicole
A1 - Huwer, Johannes
A1 - Banerji, Amitabh
T1 - Analog und digital
BT - Chemieunterricht mit Potenzial
JF - Chemie konkret : CHEMKON ; Forum für Unterricht und Didaktik
Y1 - 2022
U6 - https://doi.org/10.1002/ckon.202200046
SN - 0944-5846
SN - 1521-3730
VL - 29
SP - 182
EP - 182
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Tartivel, Lucile
A1 - Blocki, Anna M.
A1 - Braune, Steffen
A1 - Jung, Friedrich
A1 - Behl, Marc
A1 - Lendlein, Andreas
T1 - An Inverse shape-memory hydrogel scaffold switching upon cooling in a tissue-tolerated temperature range
JF - Advanced materials interfaces
N2 - Tissue reconstruction has an unmet need for soft active scaffolds that enable gentle loading with regeneration-directing bioactive components by soaking up but also provide macroscopic dimensional stability. Here microporous hydrogels capable of an inverse shape-memory effect (iSME) are described, which in contrast to classical shape-memory polymers (SMPs) recover their permanent shape upon cooling. These hydrogels are designed as covalently photo cross-linked polymer networks with oligo(ethylene glycol)-oligo(propylene glycol)-oligo(ethylene glycol) (OEG-OPG-OEG) segments. When heated after deformation, the OEG-OPG-OEG segments form micelles fixing the temporary shape. Upon cooling, the micelles dissociate again, the deformation is reversed and the permanent shape is obtained. Applicability of this iSME is demonstrated by the gentle loading of platelet-rich plasma (PRP) without causing any platelet activation during this process. PRP is highly bioactive and is widely acknowledged for its regenerative effects. Hence, the microporous inverse shape-memory hydrogel (iSMH) with a cooling induced pore-size effect represents a promising candidate scaffold for tissue regeneration for potential usage in minimally invasive surgery applications.
KW - active scaffold
KW - critical micellation temperature
KW - hydrogel
KW - inverse
KW - shape-memory effect
KW - platelet-rich plasma
Y1 - 2022
U6 - https://doi.org/10.1002/admi.202101588
SN - 2196-7350
VL - 9
IS - 6
PB - Wiley
CY - Hoboken
ER -
TY - JOUR
A1 - Machatschek, Rainhard Gabriel
A1 - Heuchel, Matthias
A1 - Lendlein, Andreas
T1 - Hydrolytic stability of polyetherimide investigated in ultrathin films
JF - Journal of materials research : JMR / Materials Research Society
N2 - Increasing the surface hydrophilicity of polyetherimide (PEI) through partial hydrolysis of the imide groups while maintaining the length of the main-chain was explored for adjusting its function in biomedical and membrane applications. The outcome of the polymer analogous reaction, i.e., the degree of ring opening and chain cleavage, is difficult to address in bulk and microstructured systems, as these changes only occur at the interface. Here, the reaction was studied at the air-water interface using the Langmuir technique, assisted by atomic force microscopy and vibrational spectroscopy. Slow PEI hydrolysis sets in at pH > 12. At pH = 14, the ring opening is nearly instantaneous. Reduction of the layer viscosity with time at pH = 14 suggested moderate chain cleavage. No hydrolysis was observed at pH = 1. Hydrolyzed PEI films had a much more cohesive structure, suggesting that the nanoporous morphology of PEI can be tuned via hydrolysis.
KW - 2D materials
KW - Membrane
KW - Polymer
KW - Water
KW - Nanostructure
Y1 - 2021
U6 - https://doi.org/10.1557/s43578-021-00267-6
SN - 0884-2914
SN - 2044-5326
VL - 36
IS - 14
SP - 2987
EP - 2994
PB - Springer
CY - Berlin
ER -
TY - JOUR
A1 - Tang, Jo Sing Julia
A1 - Smaczniak, Aline Debrassi
A1 - Tepper, Lucas
A1 - Rosencrantz, Sophia
A1 - Aleksanyan, Mina
A1 - Dähne, Lars
A1 - Rosencrantz, Ruben R.
T1 - Glycopolymer based LbL multilayer thin films with embedded liposomes
JF - Macromolecular bioscience
N2 - Layer-by-layer (LbL) self-assembly emerged as an efficient technique for fabricating coating systems for, e.g., drug delivery systems with great versatility and control. In this work, protecting group free and aqueous-based syntheses of bioinspired glycopolymer electrolytes aredescribed. Thin films of the glycopolymers are fabricated by LbL self-assembly and function as scaffolds for liposomes, which potentially can encapsulate active substances. The adsorbed mass, pH stability, and integrity of glycopolymer coatings as well as the embedded liposomes are investigated via whispering gallery mode (WGM) technology and quartz crystal microbalance with dissipation (QCM-D) monitoring , which enable label-free characterization. Glycopolymer thin films, with and without liposomes, are stable in the physiological pH range. QCM-D measurements verify the integrity of lipid vesicles. Thus, the fabrication of glycopolymer-based surface coatings with embedded and intact liposomes is presented.
KW - glycopolymers
KW - layer-by-layer self-assembly
KW - liposomes
KW - polyelectrolyte
KW - multilayer film
Y1 - 2022
U6 - https://doi.org/10.1002/mabi.202100461
SN - 1616-5187
SN - 1616-5195
VL - 22
IS - 4
PB - Wiley-VCH
CY - Weinheim
ER -
TY - THES
A1 - Breternitz, Joachim
T1 - Structural systematic investigations of photovoltaic absorber materials
N2 - The direct conversion of light from the sun into usable forms of energy marks one of the central cornerstones of the change of our living from the use of fossil, non-renewable energy resources towards a more sustainable economy. Besides the necessary societal changes necessary, it is the understanding of the solids employed that is of particular importance for the success of this target. In this work, the principles and approaches of systematic-crystallographic characterisation and systematisation of solids is used and employed to allow a directed tuning of the materials properties. The thorough understanding of the solid-state forms hereby the basis, on which more applied approaches are founded.
Two material systems, which are considered as promising solar absorber materials, are at the core of this work: halide perovskites and II-IV-N2 nitride materials. While the first is renowned for its high efficiencies and rapid development in the last years, the latter is putting an emphasis on true sustainability in that toxic and scarce elements are avoided.
N2 - Die direkte Umwandlung der Energie der Sonne bildet einen zentralen Baustein im Umbau unserer Gesellschaft von der Nutzung fossiler, nicht nachhaltiger Energieträger zum Erreichen einer nachhaltigen Wirtschaft. Neben den gesellschaftlichen Veränderungen ist es insbesondere das Verständnis der genutzten Festkörper, das den Motor dieser Entwicklung bildet. In dieser Arbeit werden Prinzipien der systematisch-kristallographischen Untersuchung und Kategorisierung von Festkörpern genutzt, um die Eigenschaften der Materialien gezielt steuern zu können. Dabei bildet das Verständnis des kristallinen Zustands und seine Untersuchung die Basis, auf der angewandtere Forschungsansätze aufbauen.
In dieser Arbeit werden vor allem zwei Materialsysteme betrachtet, die als Absorbermaterialien in Solarzellen in Betracht gezogen werden: Halid-Perowskite und II-IV-N2-Nitrid Materialien. Die ersteren zeichnen sich insbesondere durch ihre erstaunlich hohen Effizienzen und rapide Entwicklung in den letzten Jahren aus, während das letztere System in besonderer Weise auf Nachhaltigkeit optimiert ist, und giftige oder seltene Elemente zu vermeiden sucht.
KW - Materials Chemistry
KW - Crystallography
KW - Photovoltaics
Y1 - 2023
ER -
TY - JOUR
A1 - Abdou, Nicole
A1 - Alonso, Bruno
A1 - Brun, Nicolas
A1 - Landois, Perine
A1 - Taubert, Andreas
A1 - Hesemann, Peter
A1 - Mehdi, Ahmad
T1 - Ionic guest in ionic host
BT - ionosilica ionogel composites via ionic liquid confinement in ionosilica supports
JF - Materials chemistry frontiers
N2 - Ionosilica ionogels, i.e. composites consisting of an ionic liquid (IL) guest confined in an ionosilica host matrix, were synthesized via a non-hydrolytic sol-gel procedure from a tris-trialcoxysilylated amine precursor using the IL [BMIM]NTf2 as solvent. Various ionosilica ionogels were prepared starting from variable volumes of IL in the presence of formic acid. The resulting brittle and nearly colourless monoliths are composed of different amounts of IL guests confined in an ionosilica host as evidenced via thermogravimetric analysis, FT-IR, and C-13 CP-MAS solid-state NMR spectroscopy. In the following, we focused on confinement effects between the ionic host and guest. Special host-guest interactions between the IL guest and the ionosilica host were evidenced by H-1 solid-state NMR, Raman spectroscopy, and broadband dielectric spectroscopy (BDS) measurements. The three techniques indicate a strongly reduced ion mobility in the ionosilica ionogel composites containing small volume fractions of confined IL, compared to conventional silica-based ionogels. We conclude that the ionic ionosilica host stabilizes an IL layer on the host surface; this then results in a strongly reduced ion mobility compared to conventional silica hosts. The ion mobility progressively increases for systems containing higher volume fractions of IL and finally reaches the values observed in conventional silica based ionogels. These results therefore point towards strong interactions and confinement effects between the ionic host and the ionic guest on the ionosilica surface. Furthermore, this approach allows confining high volume fractions of IL into self-standing monoliths while preserving high ionic conductivity. These effects may be of interest in domains where IL phases must be anchored on solid supports to avoid leaching or IL spilling, e.g., in catalysis, in gas separation/sequestration devices or for the elaboration of solid electrolytes for (lithium-ion) batteries and supercapacitors.
Y1 - 2022
U6 - https://doi.org/10.1039/d2qm00021k
SN - 2052-1537
VL - 6
IS - 7
SP - 939
EP - 947
PB - Royal Society of Chemistry
CY - Cambridge
ER -
TY - JOUR
A1 - Bapolisi, Alain Murhimalika
A1 - Kielb, Patrycja
A1 - Bekir, Marek
A1 - Lehnen, Anne-Catherine
A1 - Radon, Christin
A1 - Laroque, Sophie
A1 - Wendler, Petra
A1 - Müller-Werkmeister, Henrike
A1 - Hartlieb, Matthias
T1 - Antimicrobial polymers of linear and bottlebrush architecture
BT - Probing the membrane interaction and physicochemical properties
JF - Macromolecular rapid communications : publishing the newsletters of the European Polymer Federation
N2 - Polymeric antimicrobial peptide mimics are a promising alternative for the future management of the daunting problems associated with antimicrobial resistance. However, the development of successful antimicrobial polymers (APs) requires careful control of factors such as amphiphilic balance, molecular weight, dispersity, sequence, and architecture. While most of the earlier developed APs focus on random linear copolymers, the development of APs with advanced architectures proves to be more potent. It is recently developed multivalent bottlebrush APs with improved antibacterial and hemocompatibility profiles, outperforming their linear counterparts. Understanding the rationale behind the outstanding biological activity of these newly developed antimicrobials is vital to further improving their performance. This work investigates the physicochemical properties governing the differences in activity between linear and bottlebrush architectures using various spectroscopic and microscopic techniques. Linear copolymers are more solvated, thermo-responsive, and possess facial amphiphilicity resulting in random aggregations when interacting with liposomes mimicking Escheria coli membranes. The bottlebrush copolymers adopt a more stable secondary conformation in aqueous solution in comparison to linear copolymers, conferring rapid and more specific binding mechanism to membranes. The advantageous physicochemical properties of the bottlebrush topology seem to be a determinant factor in the activity of these promising APs.
KW - antimicrobial polymers
KW - bottlebrush copolymers
KW - liposomes
KW - membrane
KW - interactions
KW - quartz crystal microbalance
Y1 - 2022
U6 - https://doi.org/10.1002/marc.202200288
SN - 1521-3927
SN - 1022-1336
VL - 43
IS - 19
PB - Wiley-VCH
CY - Weinheim
ER -