Double network hydrogel based on curdlan and gelatin methacryloyl (GelMA) with enhanced mechanical and tissue adhesive properties

Gelatin methacryloyl (GelMA) hydrogel based tissue-adhesives have attracted extensive attraction due to its high biocompatibility, however, it suffers from insufficient mechanical properties, low adhesion strength due to the single network. In this study, a novel double-network hydrogel (DN-GelMA-Cur) consisting of GelMA and curdlan (Cur) was developed, where the network composed by triple helix fibers of Cur induced by heating and annealing serves as the hard network, while photo-crosslinked GelMA serves as the flexible network. A series of characterizations of the hydrogels, including hydrogel-forming ability, swelling behavior, morphology, rheological and mechanical properties, tissue adhesion, and biocompatibility were performed. It was found that precursor solution, especially with lower ratios of Cur (Cur: GelMA, 2:8 and 1:9), showed better hydrogel forming ability. Those hydrogels with lower ratios of Cur had better structural maintaining abilities, higher elastic modulus compared with pure-GelMA hydrogel. Particularly, addition of lower ratios of Cur could significantly enhance tissue-adhesion strength of GelMA hydrogel. DN-GelMA-Cur hydrogels showed good cytocompatibilities, especially hydrogels with lower ratios of Cur could promote proliferation of rat peritoneal fibroblasts significantly. Therefore, DN-GelMA-Cur hydrogels with lower ratio of Cur have potential application as novel GelMA hydrogel based tissue-adhesives with enhanced mechanical and bio-adhesive properties.