Bio-inspired smart hydrogel with temperature-dependent properties and enhanced cell attachment

Stimuli-responsive smart hydrogels have been exploited for various applications, including as biomaterials with environment-dependent changes in hydrophobicity, stiffness or volume. In this study, we report the functionalisation of a temperature-responsive poly(N-isopropylacryamide) (PNIPAAm) smart hydrogel with catechol groups to enhance its stiffness and cell attachment. To introduce biomimetic adhesive catechol group, which is derived from mussel feet, a photo-crosslinkable 3-hydroxytyramine hydrochloride-derived dopamine methacrylamide (DMA) monomer was synthesised. Then, temperature-responsive smart copolymer hydrogels were successfully fabricated by photo-polymerisation of the DMA with N-isopropyl-acryamide (NIPAAm). The fabricated smart hydrogels demonstrated temperature-dependent properties, and the DMA affected the swelling behaviour and compressive mechanical strength. In vitro cell culture experiments showed that the catechol groups in the smart hydrogels promoted cell attachment and spreading. These smart hydrogels will be useful as biomaterials as tissue scaffolds with controllable properties.