Two-stage thiol-based click reactions for the preparation and adhesion of hydrogels

The fabrication of adhesive hydrogel systems is quite important for biological applications. Herein, two-stage thiol-based click reactions have been employed for the preparation and adhesion of hydrogels. In the first stage, two self-adhesive hydrogels (HG-1 and HG-2) were constructed via the thiol-based click reactions and thiol–thiol coupling reaction under different stimuli, employing the same functional copolymer poly(propargyl methacrylate-co-N-(3,4-dihydroxyphenethyl) methacrylamide-co-poly(ethylene glycol) methyl ether methacrylate) (poly(PMA-co-DMA-co-PEGMA), polyPDP) and a 4-arm thiol-PEG cross-linker. Subsequently, the two prepared hydrogels achieved responsive self-adhesion properties via the second stage of thiol-based click reactions between the preserved functional groups under different stimuli. Moreover, the self-adhered hydrogels exhibited increased mechanical strength after adhesion. The present strategy thus provides a facile approach for the fabrication of hydrogel systems with on-demand self-adhesive properties.