@article{VacogneSchopfererSchlaad2016, author = {Vacogne, Charlotte D. and Schopferer, Michael and Schlaad, Helmut}, title = {Physical Gelation of alpha-Helical Copolypeptides}, series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, volume = {17}, journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, publisher = {American Chemical Society}, address = {Washington}, issn = {1525-7797}, doi = {10.1021/acs.biomac.6b00427}, pages = {2384 -- 2391}, year = {2016}, abstract = {Owing to its rod-like alpha-helical secondary structure, the synthetic polypeptide poly(gamma-benzyl-L-glutamate) (PBLG) can form physical and thermoreversible gels in helicogenic solvents such as toluene. The versatility of PBLG can be increased by introducing functionalizable comonomers, such as allylglycine (AG). In this work we examined the secondary structure of PBLG and a series of statistical poly(gamma-benzyl-L-glutamate-co-allylglycine) copolypeptides, varying in composition and chain length, by circular dichroism (CD), Fourier-transform infrared (FTIR) and Raman spectroscopy, and wide-angle X-ray scattering (WAXS). The secondary structure of PBLG and the copolypeptides presented dissimilarities that increased with increasing AG molar fraction, especially when racemic AG units were incorporated. The physical gelation behavior of these copolypeptides was analyzed by temperature-sweep H-1 NMR and rheological measurements. The study revealed that both copolypeptide composition and chain length affected secondary structure, gelation temperature, and gel stiffness.}, language = {en} } @article{TritschlerZlotnikovFratzletal.2016, author = {Tritschler, Ulrich and Zlotnikov, Igor and Fratzl, Peter and Schlaad, Helmut and Gruener, Simon and Coelfen, Helmut}, title = {Gas barrier properties of bio-inspired Laponite-LC polymer hybrid films}, series = {PLoS one}, volume = {11}, journal = {PLoS one}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-3182}, doi = {10.1088/1748-3190/11/3/035005}, pages = {12}, year = {2016}, abstract = {Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80\%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, Laponite/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective Laponite content and the underlying composite micro-and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83\% Laponite loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these Laponite/LC polymer composites reported previously give rise to a multifunctional composite system.}, language = {en} } @article{ThielkeSeckerSchlaadetal.2016, author = {Thielke, Michael W. and Secker, Christian and Schlaad, Helmut and Theato, Patrick}, title = {Electrospinning of Crystallizable Polypeptoid Fibers}, series = {Macromolecular rapid communications}, volume = {37}, journal = {Macromolecular rapid communications}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201500502}, pages = {100 -- 104}, year = {2016}, abstract = {A unique fabrication process of low molar mass, crystalline polypeptoid fibers is described. Thermoresponsive fiber mats are prepared by electrospinning a homogeneous blend of semicrystalline poly(N-(n-propyl) glycine) (PPGly; 4.1 kDa) with high molar mass poly(ethylene oxide) (PEO). Annealing of these fibers at approximate to 100 degrees C selectively removes the PEO and produces stable crystalline fiber mats of pure PPGly, which are insoluble in aqueous solution but can be redissolved in methanol or ethanol. The formation of water-stable polypeptoid fiber mats is an important step toward their utilization in biomedical applications such as tissue engineering or wound dressing.}, language = {en} } @article{SunCernochVoelkeletal.2016, author = {Sun, Jing and Cernoch, Peter and V{\"o}lkel, Antje and Wei, Yuhan and Ruokolainen, Janne and Schlaad, Helmut}, title = {Aqueous Self-Assembly of a Protein-Mimetic Ampholytic Block Copolypeptide}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {49}, journal = {Macromolecules : a publication of the American Chemical Society}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/acs.macromol.6b00817}, pages = {5494 -- 5501}, year = {2016}, abstract = {This report describes the aggregation behavior of an ABC-type ampholytic block copolypeptide, poly(ethylene oxide)-block-poly(L-lysine)-block-poly(L-glutamate), in aqueous media in dependence of pH. Polypeptide secondary structures and self-assemblies are investigated by circular dichroism (CD), Fourier transform infrared (FT-IR) and NMR spectroscopy, zeta potential measurements, analytical ultracentrifugation (AUC), dynamic/static light scattering (DLS/SLS), and cryogenic transmission electron microscopy (cryoTEM). The polymer chains tend to form vesicles when the hydrophobic polypeptide helix is located at the chain end (acidic pH) and are existing as single chains when it is located in the center and flanked by the two hydrophilic segments (basic pH). Precipitation occurs in the intermediate pH range due to polyion complexation of the charged polypeptide segments.}, language = {en} } @article{SeckerVoelkelTierschetal.2016, author = {Secker, Christian and Voelkel, Antje and Tiersch, Brigitte and Koetz, Joachim and Schlaad, Helmut}, title = {Thermo-Induced Aggregation and Crystallization of Block Copolypeptoids in Water}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {49}, journal = {Macromolecules : a publication of the American Chemical Society}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/acs.macromol.5b02481}, pages = {979 -- 985}, year = {2016}, abstract = {Block copolypeptoids comprising a thermosensitive, crystallizable poly(N-(n-propyl)glycine) block and a watersoluble poly(N-methylglycine) block, P70My (y = 23, 42, 76, 153, and 290), were synthesized bY ring-opening polymerization of the corresponding N-alkylglycine N-carboxyanhydrides (NCAs) and examined according to their thermo-induced aggregation and crystallization in water by turbidimetty, micro-differential scanning calorimetry (micro-DSC); cryogenic scanning electron microscopy (cryo-SEM), analytical ultracentrifugation (AUC), and static light scattering (SLS). At a temperature above the cloud point temperature, the initially formed micellar aggregates started to crystallize and grow into larger complex assemblies of about 100-500 nm, exhibiting flower-like (P70M23), ellipsoidal (P70M42 and P70M72) or irregular shapes (P70M153 and.P70M290).}, language = {en} } @article{KoshkinaWestmeierLangetal.2016, author = {Koshkina, Olga and Westmeier, Dana and Lang, Thomas and Bantz, Christoph and Hahlbrock, Angelina and W{\"u}rth, Christian and Resch-Genger, Ute and Braun, Ulrike and Thiermann, Raphael and Weise, Christoph and Eravci, Murat and Mohr, Benjamin and Schlaad, Helmut and Stauber, Roland H. and Docter, Dominic and Bertin, Annabelle and Maskos, Michael}, title = {Tuning the Surface of Nanoparticles: Impact of Poly(2-ethyl-2-oxazoline) on Protein Adsorption in Serum and Cellular Uptake}, series = {Macromolecular bioscience}, volume = {16}, journal = {Macromolecular bioscience}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-5187}, doi = {10.1002/mabi.201600074}, pages = {1287 -- 1300}, year = {2016}, abstract = {Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2-ethyl-2-oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non-coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi-angle dynamic light scattering, asymmetrical flow field-flow fractionation, gel electrophoresis, and liquid chromatography-mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non-specific cellular uptake, particularly by macrophage-like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles.}, language = {en} } @article{HardyTorresRendonLealEganaetal.2016, author = {Hardy, John G. and Torres-Rendon, Jose Guillermo and Leal-Egana, Aldo and Walther, Andreas and Schlaad, Helmut and Coelfen, Helmut and Scheibel, Thomas R.}, title = {Biomineralization of Engineered Spider Silk Protein-Based Composite Materials for Bone Tissue Engineering}, series = {Materials}, volume = {9}, journal = {Materials}, publisher = {MDPI}, address = {Basel}, issn = {1996-1944}, doi = {10.3390/ma9070560}, pages = {93 -- 108}, year = {2016}, abstract = {Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering.}, language = {en} } @article{GuietUnmuessigGoebeletal.2016, author = {Guiet, Amandine and Unm{\"u}ssig, Tobias and G{\"o}bel, Caren and Vainio, Ulla and Wollgarten, Markus and Driess, Matthias and Schlaad, Helmut and Polte, J{\"o}rg and Fischer, Anna}, title = {Yolk@Shell Nanoarchitectures with Bimetallic Nanocores - Synthesis and Electrocatalytic Applications}, series = {Earth \& planetary science letters}, volume = {8}, journal = {Earth \& planetary science letters}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/acsami.6b06595}, pages = {28019 -- 28029}, year = {2016}, language = {en} } @misc{GangloffUlbrichtLorsonetal.2016, author = {Gangloff, Niklas and Ulbricht, Juliane and Lorson, Thomas and Schlaad, Helmut and Luxenhofer, Robert}, title = {Peptoids and Polypeptoids at the Frontier of Supra- and Macromolecular Engineering}, series = {Chemical reviews}, volume = {116}, journal = {Chemical reviews}, publisher = {American Chemical Society}, address = {Washington}, issn = {0009-2665}, doi = {10.1021/acs.chemrev.5b00201}, pages = {1753 -- 1802}, year = {2016}, language = {en} } @article{DoritiBrosnanWeidneretal.2016, author = {Doriti, Afroditi and Brosnan, Sarah M. and Weidner, Steffen M. and Schlaad, Helmut}, title = {Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base}, series = {Polymer Chemistry}, volume = {7}, journal = {Polymer Chemistry}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c6py00221h}, pages = {3067 -- 3070}, year = {2016}, abstract = {Polysarcosine (M-n = 3650-20 000 g mol(-1), D similar to 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator.}, language = {en} } @article{DoritiBrosnanWeidneretal.2016, author = {Doriti, Afroditi and Brosnan, Sarah M. and Weidner, Steffen M. and Schlaad, Helmut}, title = {Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base}, series = {Polymer Chemistry}, volume = {7}, journal = {Polymer Chemistry}, publisher = {RSC Publ.}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/C6PY00221H}, pages = {3067 -- 3070}, year = {2016}, abstract = {Polysarcosine (Mn = 3650-20 000 g mol-1, Đ ∼ 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator.}, language = {en} } @article{DemirelGunerVerbraekenetal.2016, author = {Demirel, A. Levent and Guner, Pinar Tatar and Verbraeken, Bart and Schlaad, Helmut and Schubert, Ulrich S. and Hoogenboom, Richard}, title = {Revisiting the Crystallization of Poly(2-alkyl-2-oxazoline)s}, series = {Journal of polymer science : B, Polymer physics}, volume = {54}, journal = {Journal of polymer science : B, Polymer physics}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0887-6266}, doi = {10.1002/polb.23967}, pages = {721 -- 729}, year = {2016}, abstract = {Poly(2-alkyl-2-oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (T-g) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt-recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 degrees C and PiPropOx between 90 and 150 degrees C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > T-g with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. (C) 2015 Wiley Periodicals, Inc.}, language = {en} }