Although several strategies are now available to enzymatically cross-link linear polymers to hydrogels for biomedical use, little progress has been reported on the use of dendritic polymers for the same purpose. Herein, we demonstrate that horseradish peroxidase (HRP) successfully catalyzes the oxidative cross-linking of a hyperbranched polyglycerol (hPG) functionalized with phenol groups to hydrogels. The tunable cross-linking results in adjustable hydrogel properties. Because the obtained materials are cytocompatible, they have great potential for encapsulating living cells for regenerative therapy. The gel formation can be triggered by glucose and controlled well under various environmental conditions.

Microfabrication has its foundations in microelectronics, where photolithography, alongside other techniques, is used to make microfabricated circuits. For use in biology, Xia and Whitesides have developed soft lithography methods to fabricate micropatterned stamps from elastomeric materials [1] which were then employed to print biofunctional molecules on cell culture dishes and glass, [2] mold a second material (replica molding) [3] and make miniaturized flow cells, i.e., microfluidic devices. [4,5] Owing to these developments, the fabrication of micro-and nanostructures for use in biology has become a large area of research spanning a wide range of applications, including biochemical assays and studies of cell adhesion and spreading. [6] Regarding the latter, surface chemistry, topography, and elasticity are known to affect and direct cell adhesion, migration, proliferation, and even differentiation. [7][8][9][10][11][12][13][14] An understanding of these factors and how they induce intracellular processes is a fundamental requirement when designing biomaterials for biomedical applications.In our studies of cellular behavior on micro-and nanopatterned hydrogels we have discovered that a surface topographic pattern induces adhesion and spreading of fibroblasts on intrinsically anti-adhesive poly(ethylene glycol) (PEG) gels. [15,16] In addition, smooth but elastically micropatterned PEG-based hydrogels enabled fibroblast adhe-We have employed our recently developed method Fill-Molding In Capillaries (FIMIC) to fabricate elastically micropatterned substrates, using two poly(ethylene glycol) (PEG)-based polymers with different elastic properties and swelling behavior. We have evaluated the FIMIC process and the quality of the eventual substrates (the ''FIMICs'') by atomic force microscopy (AFM); imaging the surface topography and quantifying the local surface elasticity. Topographical imaging reveals that the surface of the FIMICs is never perfectly smooth; a slight topographic difference of 30 nm up to several hundreds of nm is observed, with the filler material always being depressed with respect to the mold. Moreover, when the FIMICs are immersed in water (or cell culture medium), the topographical landscape changes due to differential swelling of the two constituents of the FIMICs. We have used this differential swelling to our advantage in order to diminish the topography differences present on the sample surface by employing a filler that swells more than the mold. Finally, cell culture experiments with fibroblasts underlines the topographical influence on cell adhesion on the more or less anti-adhesive PEG-based materials.B56

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We have designed and fabricated a library of polyethylene glycol (PEG)-based polymer blends, including blends of two PEG-based polymers that are liquid at room temperature where the optimisation of the blending method allows for the incorporation of higher molecular-weight PEG-based polymers which are solid at room temperature. The absence of a solvent in these blends makes them perfect candidates for use in our recently developed Fill-Molding in Capillaries (FIMIC) patterning method. As our FIMIC samples have shown to be not completely smooth (a small topography up to several nanometers has been seen previously), and this is likely to affect the cellular behaviour, we have improved our technique in order to obtain virtually smooth samples that exhibit a pattern of elasticity only. It is demonstrated that, by taking advantage of the differential swelling of the pattern components, we can level out the undesired topographic difference. In particular, by employing blends of materials, (1) the swelling degree of each component can be fine-tuned to even out any topography and (2) the use of the same blends in the sample, yet with varying cross-linker amounts, ensures the swelling degree and elasticity change without changing the surface chemistry significantly. Genuine, binary patterns of elasticity can thus be fabricated, which are a great asset to study cell migration phenomena in systematic detail.

In this study, a mask-less laser-assisted patterning method is used to fabricate welldefined cell-adhesive microdomains delimited by protein-repellent poly(ethylene glycol) (PEG) microstructures prepared from multiarm (8-PEG) macromonomers. The response of murine fibroblasts (L-929) toward these microdomains is investigated, revealing effective cell confinement within the celladhesive areas surrounded by nonadhesive 8-PEG microstructures. Moreover, the spatial positioning of cells in microdomains of various sizes and geometries is analyzed, indicating control of cell density, size, and elongated cell shape induced by the size of the microdomains and the geometric confinement.