Effect of crosslinking processing on the chemical structure and biocompatibility of a chitosan-based hydrogel

Chitosan (CS)-based hydrogels with different structures were prepared to ensure the bioavailability of bioactive components. With the electrostatic interaction between CS and anionic crosslinkers, the structure of the CS-based hydrogel changed and influenced the swelling ability, which was beneficial for maintaining bioactive ingredients in the hydrogel. Compared with sodium hexametaphosphate, hydrogels crosslinked by sodium tripolyphosphate (STPP) had a higher swelling capacity and more stable release profile (no more than 10% BSA in the upper gastrointestinal tract), which could deliver bioactive ingredients to the colon. Moreover, due to electrostatic interactions, the surface of the CS-based hydrogel became hydrophilic, which helped Caco2 cells to grow on it. 118.86%-147.22% cell viability was found on the CS-based hydrogel. Furthermore, with different crosslinkers and concentrations in the crosslinking process, the release properties and safety of the hydrogels were varied, but the STPP-crosslinked CS hydrogel presented good cell adhesivity for bioactive components to the colon.