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  - 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  - 2159-6859
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  - 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
VL  - 34
IS  - 4
SP  - 692
EP  - 700
PB  - Wiley-VCH
CY  - Weinheim
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. <br /> [GRAPHICS] <br /> .
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  -