TY - JOUR A1 - Vukicevic, Radovan A1 - Neffe, Axel T. A1 - Luetzow, Karola A1 - Pierce, Benjamin F. A1 - Lendlein, Andreas T1 - Conditional Ultrasound Sensitivity of Poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] Microgels for Controlled Lipase Release JF - Macromolecular rapid communications N2 - Triggering the release of cargo from a polymer network by ultrasonication as an external, non-invasive stimulus can be an interesting concept for on-demand release. Here, it is shown that, in pH-and thermosensitive microgels, the ultrasound sensitivity of the polymer network depends on the external conditions. Crosslinked poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] microgels showed a volume phase transition temperature (VPTT) of 25-50 degrees C, which increases with decreasing pH. Above the VPTT the polymer chains are collapsed, while below VPTT they are extended. Only in the case of maximum observed swelling, where the polymer chains are expanded, the microgels are mechanically fragmented through ultrasonication. In contrast, when the polymer chains are partially collapsed it is not possible to manipulate the microgels by ultrasound. Additionally, the ultrasound-induced on-demand release of wheat germ lipase from the microgels could be demonstrated successfully. The principle of conditional ultrasound sensitivity is likely to be general and can be used for selection of matrix-cargo combinations. KW - ultrasound KW - polymers KW - microgels KW - lipase release KW - controlled release KW - thermoresponsive polymers KW - biomaterials Y1 - 2015 U6 - https://doi.org/10.1002/marc.201500311 SN - 1022-1336 SN - 1521-3927 VL - 36 IS - 21 SP - 1891 EP - 1896 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Federico, Stefania A1 - Pierce, Benjamin F. A1 - Piluso, Susanna A1 - Wischke, Christian A1 - Lendlein, Andreas A1 - Neffe, Axel T. T1 - Design of Decorin-Based Peptides That Bind to CollagenI and their Potential as Adhesion Moieties in Biomaterials JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Mimicking the binding epitopes of protein-protein interactions by using small peptides is important for generating modular biomimetic systems. A strategy is described for the design of such bioactive peptides without accessible structural data for the targeted interaction, and the effect of incorporating such adhesion peptides in complex biomaterial systems is demonstrated. The highly repetitive structure of decorin was analyzed to identify peptides that are representative of the inner and outer surface, and it was shown that only peptides based on the inner surface of decorin bind to collagen. The peptide with the highest binding affinity for collagenI, LHERHLNNN, served to slow down the diffusion of a conjugated dye in a collagen gel, while its dimer could physically crosslink collagen, thereby enhancing the elastic modulus of the gel by one order of magnitude. These results show the potential of the identified peptides for the design of biomaterials for applications in regenerative medicine. KW - biomaterials KW - collagen KW - gels KW - peptides KW - protein-protein interactions Y1 - 2015 U6 - https://doi.org/10.1002/anie.201505227 SN - 1433-7851 SN - 1521-3773 VL - 54 IS - 37 SP - 10980 EP - 10984 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Secker, Christian A1 - Brosnan, Sarah M. A1 - Luxenhofer, Robert A1 - Schlaad, Helmut T1 - Poly(alpha-Peptoid)s Revisited: Synthesis, Properties, and Use as Biomaterial JF - Macromolecular bioscience N2 - Polypeptoids have been of great interest in the polymer science community since the early half of the last century; however, they had been basically forgotten materials until the last decades in which they have enjoyed an exciting revival. In this mini-review, we focus on the recent developments in polypeptoid chemistry, with particular focus on polymers synthesized by the ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides (NCAs). Specifically, we will review traditional monomer synthesis (such as Leuchs, Katchalski, and Kricheldorf) and recent advances in polymerization methods to yield both linear, cyclic, and functional polymers, solution and bulk thermal properties, and preliminary results on the use of polypeptoids as biomaterials (i.e immunogenicity, biodistribution, degradability, and drug delivery). KW - amino acid N-carboxyanhydride (NCA) KW - biomaterials KW - peptides KW - properties KW - ring-opening polymerization Y1 - 2015 U6 - https://doi.org/10.1002/mabi.201500023 SN - 1616-5187 SN - 1616-5195 VL - 15 IS - 7 SP - 881 EP - 891 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zhang, Quanchao A1 - Sauter, Tilman A1 - Fang, Liang A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Shape-Memory Capability of Copolyetheresterurethane Microparticles Prepared via Electrospraying JF - Macromolecular materials and engineering N2 - Multifunctional thermo-responsive and degradable microparticles exhibiting a shapememory effect (SME) have attracted widespread interest in biomedicine as switchable delivery vehicles or microactuators. In this work almost spherical solid microparticles with an average diameter of 3.9 +/- 0.9 mm are prepared via electrospraying of a copolyetheresterurethane named PDC, which is composed of crystallizable oligo(p-dioxanone) (OPDO) hard and oligo(e-caprolactone) (OCL) switching segments. The PDC microparticles are programmed via compression at different pressures and their shapememory capability is explored by off-line and online heating experiments. When a low programming pressure of 0.2 MPa is applied a pronounced thermally-induced shape-memory effect is achieved with a shape recovery ratio about 80%, while a high programming pressure of 100 MPa resulted in a weak shape-memory performance. Finally, it is demonstrated that an array of PDC microparticles deposited on a polypropylene (PP) substrate can be successfully programmed into a smart temporary film, which disintegrates upon heating to 60 degrees C. KW - biomaterials KW - microparticles KW - processing KW - stimuli-sensitive polymers KW - shape-memory effect Y1 - 2015 U6 - https://doi.org/10.1002/mame.201400267 SN - 1438-7492 SN - 1439-2054 VL - 300 IS - 5 SP - 522 EP - 530 PB - Wiley-VCH CY - Weinheim ER -