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The cell adhesion was investigated on polymer brushes of poly(2-hydroxyethyl methacrylate) (PHEMA), poly(2-hydroxyethyl acrylate) (PHEA), and poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) with different graft densities (in semidilute and concentrated regimes) and thicknesses. The concentrated polymer brushes (CPBs) of all the three, regardless of differences in chemical structure and hydrophilicity, almost completely suppressed the adhesion of L929 fibroblast cell in contrast to the corresponding semidilute polymer brushes (SDPBs). Along with our previous study on excellent protein repellency of CPB owing to its unique size-exclusion effect (of entropic origin), we concluded that such bioinertness should be commonly found in CPB of neutral and hydrophilic polymers.

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The processing of a polyelectrolyte (whose functionality is derived from its ionized functional groups) into a nanofiber may improve its functionality and yield multiple functionalities. However, the electrospinning of nanofibers from polyelectrolytes is imperfect because polyelectrolytes differ considerably from neutral polymers in their rheological properties. In our study, we attempt to solve this problem by applying a voltage of opposite polarity to charges on a polyelectrolyte. The application of this 'countervoltage' can temporarily mask or screen a specific rheological property of the polyelectrolyte, making it behave as a neutral polymer. This approach can significantly contribute to the development of new functional nanofiber materials.