Surface-attached dual-functional hydrogel for controlled cell adhesion based on poly(N,N-dimethylacrylamide)

Abstract

In this study poly(N,N-dimethylacrylamide) (PDMAA) chains that contains 5 mol% of benzophenone molecules was synthesized and coated on bare organic substrates. Upon irradiation under UV light, the photo-active benzophenone molecules enabled the formation of polymer network as well as attachment of the polymer network onto the organic substrates. From the film thickness (AFM) and photoreaction kinetics of benzophenone (UV-Vis spectroscopy), the surface density of unreacted (active) benzophenone could be controlled. Five model surfaces carrying different densities of active benzophenone were prepared by pre-irradiating approximately 1000-nm spin-coated polymer films at various irradiation energy doses. Addition of protein (laminin) as the bioactive ligands to the partially cross-linked polymeric layer followed by additional irradiation of the mixture under UV light enabled the C,H-insertion crosslinking (CHiC) process between the polymer and the bioactive ligands. This resulted in the so-called dual-functional surface that contains bioactive spots on a biopassive background. Results from immunostaining and cell adhesion experiments showed that the surface density of active benzophenone (0–2.28 × 10⁹ molecules/nm²) played role to the bioactive properties of laminin-decorated spots, while FTIR results indicated that laminin was stable upon irradiation under UV light (365 nm) up to 18 J/cm².

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