Self-healing hydrogels with stimuli responsiveness based on acylhydrazone bonds

Abstract Thermo-responsive hydrogels consist of natural and synthetic macromolecules were presented based on dynamic acylhydrazone formation, which is self-healable and pH-sensitive. Hydrazone groups modified poly(N-isopropylacrylamide) (PNIPAM) copolymers and aldehyde groups exposed oxidized sodium alginate (OSA) were adopted to prepare the functional hydrogels without any catalyst. Specifically, acylhydrazone bonds, which were served as cross-linking points, endowed the hydrogels with self-healing property confirmed by rheological recovery test. Meanwhile, the hydrogels displayed obvious reversible sol-gel transition under different conditions, leading to that the hydrogels were able to be reshaped repeatedly exposed to pH trigger. Besides, due to the PNIPAM segments were served as the frameworks, the hydrogels were testified to exhibit tunable phase transition temperature between 30 °C and 40 °C around body temperature, which was regulated by variation in aldehyde and hydrazone ratio. The as-prepared hydrogels with self-healing and dual stimuli-responsive properties are beneficial to their bioapplications as drug delivery system, biosensors and soft tissue filling agents, etc.