@article{LopezdeGuerenuKurganovaKlierHaubitzetal.2022,
author = {L{\´o}pez de Guere{\~n}u Kurganova, Anna and Klier, Dennis Tobias and Haubitz, Toni and Kumke, Michael Uwe},
title = {Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4},
series = {Photochemical \& photobiological sciences / European Society for Photobiology},
volume = {21},
journal = {Photochemical \& photobiological sciences / European Society for Photobiology},
number = {2},
publisher = {Springer},
address = {Heidelberg},
issn = {1474-905X},
doi = {10.1007/s43630-021-00161-4},
pages = {235 -- 245},
year = {2022},
abstract = {We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18\% Yb3+, 2\% Tm3+, and the influence of Gd3+ (10-50 mol\% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol\%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.},
language = {en}
}
@article{LiuGouldKratzetal.2022,
author = {Liu, Yue and Gould, Oliver E. C. and Kratz, Karl and Lendlein, Andreas},
title = {On demand sequential release of (sub)micron particles controlled by size and temperature},
series = {Small : nano micro},
volume = {18},
journal = {Small : nano micro},
number = {5},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {1613-6810},
doi = {10.1002/smll.202104621},
pages = {8},
year = {2022},
abstract = {Polymeric devices capable of releasing submicron particles (subMP) on demand are highly desirable for controlled release systems, sensors, and smart surfaces. Here, a temperature-memory polymer sheet with a programmable smooth surface served as matrix to embed and release polystyrene subMP controlled by particle size and temperature. subMPs embedding at 80 degrees C can be released sequentially according to their size (diameter D of 200 nm, 500 nm, 1 mu m) when heated. The differences in their embedding extent are determined by the various subMPs sizes and result in their distinct release temperatures. Microparticles of the same size (D approximate to 1 mu m) incorporated in films at different programming temperatures T-p (50, 65, and 80 degrees C) lead to a sequential release based on the temperature-memory effect. The change of apparent height over the film surface is quantified using atomic force microscopy and the realization of sequential release is proven by confocal laser scanning microscopy. The demonstration and quantification of on demand subMP release are of technological impact for assembly, particle sorting, and release technologies in microtechnology, catalysis, and controlled release.},
language = {en}
}
@article{KuntzeViljakkaTitovetal.2022,
author = {Kuntze, Kim and Viljakka, Jani and Titov, Evgenii and Ahmed, Zafar and Kalenius, Elina and Saalfrank, Peter and Priimagi, Arri},
title = {Towards low-energy-light-driven bistable photoswitches},
series = {Photochemical \& photobiological sciences / European Society for Photobiology},
volume = {21},
journal = {Photochemical \& photobiological sciences / European Society for Photobiology},
number = {2},
publisher = {Springer},
address = {Heidelberg},
issn = {1474-905X},
doi = {10.1007/s43630-021-00145-4},
pages = {159 -- 173},
year = {2022},
abstract = {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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language = {en}
}
@phdthesis{Nie2022,
author = {Nie, Yan},
title = {Modulating keratinocyte and induced pluripotent stem cell behavior by microenvironment design or temperature control},
pages = {xiv, 100},
year = {2022},
abstract = {Under the in vivo condition, a cell is continually interacting with its surrounding microenvironment, which is composed of its neighboring cells and the extracellular matrix (ECM). These components generate and transmit the microenvironmental signals to regulate the fate and function of the target cells. Except the signals from the microenvironment, stimuli from the ambient environment, such as temperature changes, also play an important in modulating the cell behaviors, which are considered as regulators from the macroenvironment. In this regard, recapitulation of these environmental factors to steer cell function will be of crucial importance for therapeutic purposes and tissue regeneration. Although the role of a variety of environmental factors has been evaluated, it is still challenging to identify and provide the appropriate factors, which are required for optimizing the survival of cells and for ensuring effective cell functions. Thus, in vitro recreating the environmental factors that are present in the extracellular environment would help to understand the mechanism of how cells sense and process those environmental signals. In this context, this thesis is aimed to harness these environmental parameters to guide cell responses. Here, human induced pluripotent stem cells (hiPSCs) and human keratinocytes (KTCs), HaCaT cells, were used to investigate the impact of signals from the microenvironment or stimuli from the macroenvironment. Firstly, polydopamine (PDA) or chitosan (CS) modifications were applied to generate different substrate surfaces for hiPSCs and KTCs (Chapter 4 to Chapter 6). Our results showed that the PDA modification was efficient to increase the cell-substrate adhesion and consequently promoted cell spreading. While CS modification was able to decrease the cell-substrate adhesion and enhance the cell-cell interaction, which enabled the morphology shift from monolayered cells to multicellular spheroids. The quantitative result was acquired using the atomic force microscopy (AFM)-based single-cell force spectroscopy. The balance between the cell-substrate and cell-cell adhesion yielded a net force, which determined the preference of the cell to adhere to its neighboring cells or to the substrate. The difference in the adhesive behaviors further affected the cellular function, such as the proliferation and differentiation potential of both hiPSCs and HaCaT cells. Next, the cyclic temperature changes (ΔT) were selected here to study the influence of macroenvironmental stimuli on hiPSCs and KTCs (Chapter 7 and Chapter 8). The macroenvironmental temperature ranging from 10.0 ± 0.1 °C to 37.0 ± 0.1 °C was achieved using a thermal chamber equipped with a temperature controller. This temperature range was selected to explore the responses of hiPSCs to the extreme environments, while a temperature variation between 25.0 ± 0.1 °C and 37.0 ± 0.1 °C was applied to mimic the ambient temperature variations experienced by the skin epithelial KTCs. The ΔT led to cell stiffening in both hiPSCs and HaCaT cells in a cytoskeleton-dependent manner, which was measured by AFM. Specifically, in hiPSCs, the cell stiffening was resulted from the rearrangement of the actin skeleton; in HaCaT cells, was due to the difference of the Keratin (KRT) filaments. Except for inducing cell hardening, ΔT also caused differences in the protein expression profiles in hiPSCs or HaCaT cells, compared to those without ΔT treatment, which might be attributed to the alterations in their cytoskeleton structures. To sum up, the results of the thesis demonstrated how individual factors from the micro-/macro-environment can be harnessed to modulate the behaviors of hiPSCs and HaCaT cells. Engineering the microenvironmental cues using surface modification and exploiting the macroenvironmental stimuli through temperature control were identified as precise and potent approaches to steer hiPSC and HaCaT cell behaviors. The application of AFM served as a non-invasive and real-time monitoring platform to trace the change in cell topography and mechanics induced by the environmental signals, which provide novel insights into the cell-environment interactions.},
language = {en}
}
@article{TungMaringXuetal.2022,
author = {Tung, Wing Tai and Maring, Janita A. and Xu, Xun and Liu, Yue and Becker, Matthias and Somesh, Dipthi Bachamanda and Klose, Kristin and Wang, Weiwei and Sun, Xianlei and Ullah, Imran and Kratz, Karl and Neffe, Axel T. and Stamm, Christof and Ma, Nan and Lendlein, Andreas},
title = {In vivo performance of a cell and factor free multifunctional fiber mesh modulating postinfarct myocardial remodeling},
series = {Advanced Functional Materials},
volume = {32},
journal = {Advanced Functional Materials},
number = {31},
publisher = {Wiley},
address = {Weinheim},
issn = {1616-301X},
doi = {10.1002/adfm.202110179},
pages = {17},
year = {2022},
abstract = {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.},
language = {en}
}
@article{SandmannMuenzbergBresseletal.2022,
author = {Sandmann, Michael and M{\"u}nzberg, Marvin and Bressel, Lena and Reich, Oliver and Hass, Roland},
title = {Inline monitoring of high cell density cultivation of Scenedesmus rubescens in a mesh ultra-thin layer photobioreactor by photon density wave spectroscopy},
series = {BMC Research Notes / Biomed Central},
volume = {15},
journal = {BMC Research Notes / Biomed Central},
number = {1},
publisher = {Biomed Central (London)},
address = {London},
issn = {1756-0500},
doi = {10.1186/s13104-022-05943-2},
pages = {7},
year = {2022},
abstract = {Objective Due to multiple light scattering that occurs inside and between cells, quantitative optical spectroscopy in turbid biological suspensions is still a major challenge. This includes also optical inline determination of biomass in bioprocessing. Photon Density Wave (PDW) spectroscopy, a technique based on multiple light scattering, enables the independent and absolute determination of optical key parameters of concentrated cell suspensions, which allow to determine biomass during cultivation. Results A unique reactor type, called "mesh ultra-thin layer photobioreactor" was used to create a highly concentrated algal suspension. PDW spectroscopy measurements were carried out continuously in the reactor without any need of sampling or sample preparation, over 3 weeks, and with 10-min time resolution. Conventional dry matter content and coulter counter measurements have been employed as established offline reference analysis. The PBR allowed peak cell dry weight (CDW) of 33.4 g L-1. It is shown that the reduced scattering coefficient determined by PDW spectroscopy is strongly correlated with the biomass concentration in suspension and is thus suitable for process understanding. The reactor in combination with the fiber-optical measurement approach will lead to a better process management.},
language = {en}
}
@article{FudickarMetzMaiLindeetal.2021,
author = {Fudickar, Werner and Metz, Melanie and Mai-Linde, Yasemin and Kr{\"u}ger, Tobias and Kelling, Alexandra and Sperlich, Eric and Linker, Torsten},
title = {Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes},
series = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
volume = {97},
journal = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
number = {6},
publisher = {Wiley},
address = {Malden, Mass.},
issn = {0031-8655},
doi = {10.1111/php.13422},
pages = {1289 -- 1297},
year = {2021},
abstract = {The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a "large-group effect" of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a "spiro effect" in singlet oxygen ene reactions.},
language = {en}
}
@article{RajuKoetz2021,
author = {Raju, Rajarshi Roy and Koetz, Joachim},
title = {Inner rotation of Pickering Janus emulsions},
series = {Nanomaterials : open access journal},
volume = {11},
journal = {Nanomaterials : open access journal},
number = {12},
publisher = {MDPI},
address = {Basel},
issn = {2079-4991},
doi = {10.3390/nano11123312},
pages = {6},
year = {2021},
abstract = {Janus droplets were prepared by vortex mixing of three non-mixable liquids, i.e., olive oil, silicone oil and water, in the presence of gold nanoparticles (AuNPs) in the aqueous phase and magnetite nanoparticles (MNPs) in the olive oil. The resulting Pickering emulsions were stabilized by a red-colored AuNP layer at the olive oil/water interface and MNPs at the oil/oil interface. The core-shell droplets can be stimulated by an external magnetic field. Surprisingly, an inner rotation of the silicon droplet is observed when MNPs are fixed at the inner silicon droplet interface. This is the first example of a controlled movement of the inner parts of complex double emulsions by magnetic manipulation via interfacially confined magnetic nanoparticles.},
language = {en}
}
@article{Picconi2021,
author = {Picconi, David},
title = {Nonadiabatic quantum dynamics of the coherent excited state intramolecular proton transfer of 10-hydroxybenzo[h]quinoline},
series = {Photochemical \& photobiological sciences},
volume = {20},
journal = {Photochemical \& photobiological sciences},
number = {11},
publisher = {Springer},
address = {Heidelberg},
issn = {1474-905X},
doi = {10.1007/s43630-021-00112-z},
pages = {1455 -- 1473},
year = {2021},
abstract = {The photoinduced nonadiabatic dynamics of the enol-keto isomerization of 10-hydroxybenzo[h]quinoline (HBQ) are studied computationally using high-dimensional quantum dynamics. The simulations are based on a diabatic vibronic coupling Hamiltonian, which includes the two lowest pi pi* excited states and a n pi* state, which has high energy in the Franck-Condon zone, but significantly stabilizes upon excited state intramolecular proton transfer. A procedure, applicable to large classes of excited state proton transfer reactions, is presented to parametrize this model using potential energies, forces and force constants, which, in this case, are obtained by time-dependent density functional theory. The wave packet calculations predict a time scale of 10-15 fs for the photoreaction, and reproduce the time constants and the coherent oscillations observed in time- resolved spectroscopic studies performed on HBQ. In contrast to the interpretation given to the most recent experiments, it is found that the reaction initiated by 1 pi pi* <- S-0 photoexcitation proceeds essentially on a single potential energy surface, and the observed coherences bear signatures of Duschinsky mode-mixing along the reaction path. The dynamics after the 2 pi pi* <- S-0 excitation are instead nonadiabatic, and the n pi* state plays a major role in the relaxation process. The simulations suggest a mainly active role of the proton in the isomerization, rather than a passive migration assisted by the vibrations of the benzoquinoline backbone.
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language = {en}
}
@phdthesis{Nacak2021,
author = {Nacak, Selma},
title = {Synthesis and Characterization of Upconversion Nanaparticles for Applications in Life Sciences},
school = {Universit{\"a}t Potsdam},
year = {2021},
language = {en}
}
@article{NeffeIzraylitHommesSchattmannetal.2021,
author = {Neffe, Axel T. and Izraylit, Victor and Hommes-Schattmann, Paul J. and Lendlein, Andreas},
title = {Soft, formstable (Co)polyester blend elastomers},
series = {Nanomaterials : open access journal},
volume = {11},
journal = {Nanomaterials : open access journal},
number = {6},
publisher = {MDPI},
address = {Basel},
issn = {2079-4991},
doi = {10.3390/nano11061472},
pages = {18},
year = {2021},
abstract = {High crystallization rate and thermomechanical stability make polylactide stereocomplexes effective nanosized physical netpoints. Here, we address the need for soft, form-stable degradable elastomers for medical applications by designing such blends from (co)polyesters, whose mechanical properties are ruled by their nanodimensional architecture and which are applied as single components in implants. By careful controlling of the copolymer composition and sequence structure of poly[(L-lactide)-co-(epsilon-caprolactone)], it is possible to prepare hyperelastic polymer blends formed through stereocomplexation by adding poly(D-lactide) (PDLA). Low glass transition temperature T-g <= 0 degrees C of the mixed amorphous phase contributes to the low Young's modulus E. The formation of stereocomplexes is shown in DSC by melting transitions T-m > 190 degrees C and in WAXS by distinct scattering maxima at 2 theta = 12 degrees and 21 degrees. Tensile testing demonstrated that the blends are soft (E = 12-80 MPa) and show an excellent hyperelastic recovery R-rec = 66-85\% while having high elongation at break epsilon(b) up to >1000\%. These properties of the blends are attained only when the copolymer has 56-62 wt\% lactide content, a weight average molar mass >140 kg center dot mol(-1), and number average lactide sequence length >= 4.8, while the blend is formed with a content of 5-10 wt\% of PDLA. The devised strategy to identify a suitable copolymer for stereocomplexation and blend formation is transferable to further polymer systems and will support the development of thermoplastic elastomers suitable for medical applications.},
language = {en}
}
@article{FudickarRoderListeketal.2021,
author = {Fudickar, Werner and Roder, Phillip and Listek, Martin and Hanack, Katja and Linker, Torsten},
title = {Pyridinium alkynylanthracenes as sensitizers for photodynamic therapy},
series = {Photochemistry and photobiology},
volume = {98},
journal = {Photochemistry and photobiology},
number = {1},
publisher = {Wiley},
address = {Hoboken},
issn = {0031-8655},
doi = {10.1111/php.13554},
pages = {193 -- 201},
year = {2021},
abstract = {Photodynamic therapy (PDT) is a mild but effective method to treat certain types of cancer upon irradiation with visible light. Here, three isomeric methylpyridinium alkynylanthracenes 1op were evaluated as sensitizers for PDT. Upon irradiation with blue or green light, all three compounds show the ability to initiate strand breaks of plasmid DNA. The mayor species responsible for cleavage is singlet oxygen (O-1(2)) as confirmed by scavenging reagents. Only isomers 1m and 1p can be incorporated into HeLa cells, whereas isomer 1o cannot permeate through the membrane. While isomer 1m targets the cell nucleus, isomer 1p assembles in the cellular cytoplasm and impacts the cellular integrity. This is in accordance with a moderate toxicity of 1p in the dark, whereas 1m exhibits no dark toxicity. Both isomers are suitable as PDT reagents, with a CC50 of 3 mu m and 75 nm, for 1p and 1m, respectively. Thus, derivative 1m, which can be easily synthesized, becomes an interesting candidate for cancer therapy.},
language = {en}
}
@article{NeffeLoewenbergJulichGruneretal.2021,
author = {Neffe, Axel T. and L{\"o}wenberg, Candy and Julich-Gruner, Konstanze K. and Behl, Marc and Lendlein, Andreas},
title = {Thermally-induced shape-memory behavior of degradable gelatin-based networks},
series = {International journal of molecular sciences},
volume = {22},
journal = {International journal of molecular sciences},
number = {11},
publisher = {Molecular Diversity Preservation International},
address = {Basel},
issn = {1422-0067},
doi = {10.3390/ijms22115892},
pages = {15},
year = {2021},
abstract = {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.},
language = {en}
}
@article{LauMaierBrauneetal.2021,
author = {Lau, Skadi and Maier, Anna and Braune, Steffen and Gossen, Manfred and Lendlein, Andreas},
title = {Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials},
series = {International journal of molecular sciences},
volume = {22},
journal = {International journal of molecular sciences},
number = {13},
publisher = {Molecular Diversity Preservation International},
address = {Basel},
issn = {1422-0067},
doi = {10.3390/ijms22137006},
pages = {13},
year = {2021},
abstract = {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.},
language = {en}
}
@article{SchoenemannKocKarthaeuseretal.2021,
author = {Sch{\"o}nemann, Eric and Koc, Julian and Karth{\"a}user, Jana and {\"O}zcan, Onur and Schanzenbach, Dirk and Schardt, Lisa and Rosenhahn, Axel and Laschewsky, Andr{\´e}},
title = {Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties},
series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences},
volume = {22},
journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences},
number = {4},
publisher = {American Chemical Society},
address = {Washington},
issn = {1525-7797},
doi = {10.1021/acs.biomac.0c01705},
pages = {1494 -- 1508},
year = {2021},
abstract = {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.},
language = {en}
}
@article{TungSunWangetal.2021,
author = {Tung, Wing Tai and Sun, Xianlei and Wang, Weiwei and Xu, Xun and Ma, Nan and Lendlein, Andreas},
title = {Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films},
series = {MRS advances : a journal of the Materials Research Society (MRS)},
volume = {6},
journal = {MRS advances : a journal of the Materials Research Society (MRS)},
number = {10},
publisher = {Springer Nature Switzerland AG},
address = {Cham},
issn = {2059-8521},
doi = {10.1557/s43580-020-00001-0},
pages = {276 -- 282},
year = {2021},
abstract = {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.},
language = {en}
}
@article{FigueroaCamposPerezBlocketal.2021,
author = {Figueroa Campos, Gustavo Adolfo and Perez, Jeffrey Paulo H. and Block, Inga and Sagu Tchewonpi, Sorel and Saravia Celis, Pedro and Taubert, Andreas and Rawel, Harshadrai Manilal},
title = {Preparation of activated carbons from spent coffee and coffee parchment and assessment of their adsorbent efficiency},
series = {Processes : open access journal},
volume = {9},
journal = {Processes : open access journal},
number = {8},
publisher = {MDPI},
address = {Basel},
issn = {2227-9717},
doi = {10.3390/pr9081396},
pages = {18},
year = {2021},
abstract = {The valorization of coffee wastes through modification to activated carbon has been considered as a low-cost adsorbent with prospective to compete with commercial carbons. So far, very few studies have referred to the valorization of coffee parchment into activated carbon. Moreover, low-cost and efficient activation methods need to be more investigated. The aim of this work was to prepare activated carbon from spent coffee grounds and parchment, and to assess their adsorption performance. The co-calcination processing with calcium carbonate was used to prepare the activated carbons, and their adsorption capacity for organic acids, phenolic compounds and proteins was evaluated. Both spent coffee grounds and parchment showed yields after the calcination and washing treatments of around 9.0\%. The adsorption of lactic acid was found to be optimal at pH 2. The maximum adsorption capacity of lactic acid with standard commercial granular activated carbon was 73.78 mg/g, while the values of 32.33 and 14.73 mg/g were registered for the parchment and spent coffee grounds activated carbons, respectively. The Langmuir isotherm showed that lactic acid was adsorbed as a monolayer and distributed homogeneously on the surface. Around 50\% of total phenols and protein content from coffee wastewater were adsorbed after treatment with the prepared activated carbons, while 44, 43, and up to 84\% of hydrophobic compounds were removed using parchment, spent coffee grounds and commercial activated carbon, respectively; the adsorption efficiencies of hydrophilic compounds ranged between 13 and 48\%. Finally, these results illustrate the potential valorization of coffee by-products parchment and spent coffee grounds into activated carbon and their use as low-cost adsorbent for the removal of organic compounds from aqueous solutions.},
language = {en}
}
@inproceedings{RamadanGuerreroNedielkovetal.2021,
author = {Ramadan, Shahenda and Guerrero, Paula and Nedielkov, Ruslan and Klishin, Nikolai and Dimova, Rumiana and Silva, Daniel V. and M{\"o}ller, Heiko},
title = {Building a mimetic system for unraveling protein-protein interactions on membranes},
series = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
volume = {50},
booktitle = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
number = {SUPPL 1},
publisher = {Springer},
address = {Berlin ; Heidelberg ; New York},
issn = {0175-7571},
doi = {10.1007/s00249-021-01558-w},
pages = {S153 -- S153},
year = {2021},
language = {en}
}
@article{BuyinzaDereseNdakalaetal.2021,
author = {Buyinza, Daniel and Derese, Solomon and Ndakala, Albert and Heydenreich, Matthias and Yenesew, Abiy and Koch, Andreas and Oriko, Richard},
title = {A coumestan and a coumaronochromone from Millettia lasiantha},
series = {Biochemical systematics and ecology},
volume = {97},
journal = {Biochemical systematics and ecology},
publisher = {Elsevier},
address = {Oxford},
issn = {0305-1978},
doi = {10.1016/j.bse.2021.104277},
pages = {5},
year = {2021},
abstract = {The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and las-coumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.},
language = {en}
}
@article{BastianRobelSchmidtetal.2021,
author = {Bastian, Philipp U. and Robel, Nathalie and Schmidt, Peter and Schrumpf, Tim and G{\"u}nter, Christina and Roddatis, Vladimir and Kumke, Michael Uwe},
title = {Resonance energy transfer to track the motion of lanthanide ions},
series = {Biosensors : open access journal},
volume = {11},
journal = {Biosensors : open access journal},
number = {12},
publisher = {MDPI},
address = {Basel},
issn = {2079-6374},
doi = {10.3390/bios11120515},
pages = {23},
year = {2021},
abstract = {The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF4 and NaGdF4 was monitored. These investigations have been performed by laser spectroscopy with help of lanthanide resonance energy transfer (LRET) between Eu(III) as donor and Pr(III) or Nd(III) as acceptor. The LRET is evaluated based on the Forster theory. The findings corroborate the literature and point out the migration of ions in the host lattices. Based on the introduced LRET model, the acceptor concentration in the surrounding of one donor depends clearly on the design of the applied core-shell-shell nanoparticles. In general, thinner intermediate insulating shells lead to higher acceptor concentration, stronger quenching of the Eu(III) donor and subsequently stronger sensitization of the Pr(III) or the Nd(III) acceptors. The choice of the host lattice as well as of the synthesis temperature are parameters to be considered for the intermixing process.},
language = {en}
}