Injectable photo crosslinked enhanced double-network hydrogels from modified sodium alginate and gelatin

Recently, photocrosslinked hydrogels have attracted more and more attention in biomedical applications. In this study, a serials of injectable hydrogels were fabricated from aldehyde methacrylate sodium alginate and amino gelatin (AMSA/AG) using a two-step process. Here, sodium alginate, a kind of natural polysaccharide, was modified by oxidizer to form aldehyde sodium alginate (ASA), and methacrylate groups were further grafted on the main chain of ASA. Gelatin, the denatured form of collagen, was modified with ethylenediamine (ED) to graft more amino groups. When AMSA and AG aqueous solutions were mixed, the Schiff base reaction occurred quickly to form the primary network between aldehyde groups in AMSA and amino groups in AG, and then a 365 nm ultraviolet (UV) light was used to initiate the radical reaction of methacrylate groups in AMSA to produce the secondary network. The structures and properties of AMSA/AG hydrogels were evaluated by Fourier Transforms Infrared spectroscopy (FTIR) and 1HNMR analysis. The swelling ratio confirmed the density of crosslinked networks, and the mechanical performance demonstrated that the UV initiated the double crosslinking network hydrogels have an improved mechanical properties compared to the single Schiff base networks hydrogels. The results showed that the photocrosslinked double network hydrogels have enhanced mechanical properties, good biocompatibility and controllable degradation rate. So, this hydrogels may have great potential utilized in regenerative medicine as therapeutic materials.