Design and fabrication of biocompatible wrinkled hydrogel films with selective antibiofouling properties

In this article, we explored the selective antibiofouling capacity acquired by functional wrinkled hydrogel films via a fine tuning of their chemical structure through the gradual insertion of hydrophobic radical groups in their network. The hydrogel consists of three main components: hydroxyethyl methacrylate (HEMA, amphiphilic monomer), trifluoroethyl methacrylate (TFMA, hydrophobic monomer), and poly(ethylene glycol) diacrylate (PEGDA, hydrophilic crosslinking agent). Interestingly, the manipulation of the chemical composition affects both, surface morphology and physicochemical characteristics of the patterns, inducing transitions between different surface microstructures, i.e. from wrinkles to creases, to folds, and to crumples. Contact angle measurements show that the insertion of TFMA produces a slight decrease in surface wettability, remaining however highly hydrophilic. By using confocal Raman spectroscopy, important information about wrinkle formation mechanism could be obtained. The procedure presented in this article involves two consecutive thermal and photopolymerization steps, generating a "pseudo" two-layer system, which contracts at different extents when is exposed to external stimuli, leading to the formation of wrinkled surfaces. Finally, bacterial and cellular adhesion/proliferation studies were carried out, evidencing that the amount of TFMA included clearly reduce the bacterial adhesion while mammalian cells are able to still proliferate.