Synthesis and characterization of biodegradable thermoresponsive N-maleyl gelatin-co-P(N-isopropylacrylamide) hydrogel cross-linked with Bis-acrylamide for control release

Biodegradable N-maleyl gelatin (N-MAGEL) was synthesized with gelatin (GEL) and maleic anhydride (MAH) by acylation. With Bis-acrylamide (Bis) cross-linker, a series of cross-linked poly (N-isopropylacrylamide-co-N-maleyl gelatin) [P(NIPAAm-co-N-MAGEL)] hydrogels were prepared, and their lower critical solution temperature (LCST), water content, swelling/deswelling kinetics, drug delivery behaviors, and enzymatic degradation properties were investigated. As weight ratios of N-MAGEL/NIPAAm in hydrogel were increasing, water content increased, and it had no significant influence on LCST of hydrogel in spite of the weight ratios reaching 30:70. In the swelling/deswelling kinetics, hydrogels with higher weight ratios of N-MAGEL/NIPAAm exhibited faster swelling rate and slower deswelling rate. Drug delivery for bovine serum albumin (BSA) research indicated that increasing weight ratios of N-MAGEL/NIPAAm in hydrogels contribute to raising release time and cumulative release ratios. Lastly, hydrogels with higher weight ratios of N-MAGEL/NIPAAm degraded rapidly in phosphate-buffered saline (PBS) containing papain.