Preparation and Properties of Self-Cross-Linking Hydrogels Based on Chitosan Derivatives and Oxidized Sodium Alginate

A self-cross-linking and biocompatible hydrogel has wide application potential in the field of tissue engineering. In this work, an easily available, biodegradable, and resilient hydrogel was prepared using a self-cross-linking method. This hydrogel was composed of N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and oxidized sodium alginate (OSA). A stable and reversible cross-linking network was formed by the Schiff base self-cross-linked and hydrogen bonding. The addition of a shielding agent (NaCl) may weaken the intense electrostatic effect between HACC and OSA and solve the problem of flocculation caused by the rapid formation of ionic bonds, which provided an extended time for the Schiff base self-cross-linked reaction for forming a homogeneous hydrogel. Interestingly, the shortest time for the formation of the HACC/OSA hydrogel was within 74 s and the hydrogel had a uniform porous structure and enhanced mechanical properties. The HACC/OSA hydrogel withstood large compression deformation due to improved elasticity. What's more, this hydrogel possessed favorable swelling property, biodegradation, and water retention. The HACC/OSA hydrogels have great antibacterial properties against Staphylococcus aureus and Escherichia coli and demonstrated good cytocompatibility as well. The HACC/OSA hydrogels have a good sustained release effect on rhodamine (model drug). Thus, the obtained self-cross-linked HACC/OSA hydrogels in this study have potential applications in the field of biomedical carriers.