Highly efficient alginate-based macromolecular photoinitiator for crosslinking and toughening gelatin hydrogels

Constructing gelatin hydrogels through photopolymerization is getting increasingly attractive due to their excellent biocompatibility and unparalleled flexibility in fabricating complex structures. In this study, an alginate-based macromolecular photoinitiator (Alg-2959) is synthesized by grafting Irgacure2959, a widely used hydrophilic small molecular photoinitiator, onto the framework of alginate. The characterization of Alg-2959 is carried out by H-1 nuclear magnetic resonance ((HNMR)-H-1), Fourier infrared spectroscopic (FTIR), Thermogravimetric analysis (TGA), and UV-Vis absorption spectrum. It is shown that Alg-2959 can induce the polymerization of acrylate monomer poly(ethylene glycol) diacrylate (PEGDA400) and glycidyl methacrylate modified gelatin (Gel-GM) with similar initiation efficiency as Irgacure2959. Compared with the pure hydrogels prepared using Irgacure2959, the hybrid hydrogels containing Alg-2959 can be further crosslinked by Ca2+ to form the double-network hydrogels, which exhibit enhanced toughness and elasticity. In addition, due to the introduction of alginate, the migration stability of Alg-2959 in the hydrogel networks is significantly improved compared with Irgacure2959. These results indicate the great potential of Alg-2959 in preparing biocompatible and resilient photopolymers.