Novel electrospun materials for bone tissue engineering were obtained by blending biodegradable polyhydroxybutyrate (PHB) or polyhydroxybutyrate valerate (PHBV) with the anionic sulfated polysaccharide κ-carrageenan (κ-CG) in varying ratios. In both systems, the two components phase separated as shown by FTIR, DSC and TGA. According to the contact angle data, κ-CG was localized preferentially at the fiber surface in PHBV/κ-CG blends in contrast to PHB/κ-CG, where the biopolymer was mostly found within the fiber. In contrast to the neat polyester fibers, the blends led to the formation of much smaller apatite crystals (800 nm vs 7 μm). According to the MTT assay, NIH3T3 cells grew in higher density on the blend mats in comparison to neat polyester mats. The osteogenic differentiation potential of the fibers was determined by SaOS-2 cell culture for 2 weeks. Alizarin red-S staining suggested an improved mineralization on the blend fibers. Thus, PHBV/κ-CG fibers resulted in more pronounced bioactive and osteogenic properties, including fast apatite-forming ability and deposition of nanosized apatite crystals.

An ew concept enables the generation of cell microenvironments by microobject assembly at an water/air interface.Asthe orientation of 30 mmsized polymer cubes and their capillary force assembly are controlled by the surface wettability,w hich in turn can be modulated by coating the initially exposed surfaces with gold and self-assembled monolayers,u nique niches in closely packed arrays of cubes with vertex up orientation can be realized. The random assembly of distinctly different cubes,p refunctionalized or surface-structured exclusively on their top surface,f acilitates the parallel generation of different microenvironments in ac ombinatorial manner,w hichp aves the wayt of uture systematic structureproperty relationship studies with cells.

Summary Polymer brush synthesis by surface initiated polymerization (SIP) comprises a powerful strategy to tailor interfacial properties. Among others, the passivation of solid substrates against non‐specific protein adsorption or the implementation of stimuli responsive properties can be achieved. In this context controlled radical polymerization approaches are frequently employed. Here we report on our efforts in the synthesis of oligo and di(ethylene glycol) methylether methacrylate (OEGMA and DEGMA)‐based brushes with (i) controlled grafting density and (ii) new diblock copolymer structures. We assembled mixed self‐assembled monolayers (SAMs) comprising octadecanethiol (ODT), 16‐mercaptohexadecanoic (MHDA) and ω‐mercaptoundecyl bromoisobutyrate (MUBiB) on gold to initiate the controlled radical polymerization of OEGMA and DEGMA. The SAMs as well as the polymer layers obtained by atom transfer radical polymerization for a constant polymerization time were characterized by contact angle measurements with water, FTIR spectroscopy, ellipsometry and atomic force microscopy (AFM). It was found that ODT and MHDA assemble in the mixed SAMs preferentially and despite the different endgroups very similar brushes were obtained. SAMs with fractional surface coverages of the initiator ω‐mercaptoundecyl bromoisobutyrate of > 0.45 showed no further increase in brush thickness, which is in line with a mushroom to brush transition below this coverage. In addition, diblock copolymer brushes comprising POEGMA and poly(tert‐butyl acrylate) (PtBA) blocks were obtained for the first time. The PtBA block was successfully hydrolyzed to yield POEGMA‐block‐poly acrylic acid (PAA) brushes.

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Summary Polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) diblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Self‐assembly of these block copolymers into polymeric vesicles, so‐called polymersomes, was performed by addition of water to a solution of the block copolymers in tetrahydrofuran (THF). Various antimicrobial compounds and dyes were incorporated in the polymersomes and in addition to the corresponding size distributions, as determined by dynamic light scattering (DLS), the maximum attainable loading concentrations were determined. Using the release of incorporated calcein, which is a pH responsive dye, the principle of a light up probe approach for advanced in situ diagnostics was demonstrated. The release from PS‐b‐PAA vesicles via a vesicle‐to‐micelle transition was triggered by heating a vesicle suspension after addition of the plasticizer THF to 50 °C. Furthermore, a biocompatible and degradable block copolymer system, which contains degradable ester bonds in the main chain, was synthesized and investigated. In particular, poly(ethylene glycol)‐block‐polycaprolactone (PEG‐b‐PCL) copolymers were synthesized via ring‐opening polymerization (ROP). These copolymers were shown to form polymersomes as well and represent a promising family of degradable amphiphilic block copolymers for active wound dressings and related applications.