A pH-responsive dual-network biopolysaccharide hydrogel with enhanced self-healing and controlled drug release properties

Traditional hydrogels based on Schiff base reactions frequently encounter issues with rapid drug release when employed as drug delivery systems owing to their susceptibility to hydrolysis under acidic conditions. It is, therefore, necessary to implement improvements to regulate the drug release behavior. In this study, a dual-network and pH-responsive biopolysaccharide hydrogel was developed, which is self-healing, injectable and biocompatible. Most importantly, the hydrogel has excellent tunability for controlled drug release. The hydrogel consisted of a primary network of dibenzaldehyde-functionalized poly(ethylene glycol) (DP) and chitosan (CS) formed through a Schiff base reaction and a secondary network of sodium alginate (SA) and CS formed through electrostatic interactions. It was found that the DP–CS–2%SA hydrogel can prolong the release duration up to four-fold compared to the single-network DP–CS hydrogel at a given release threshold. Significantly, by adjusting the relationship between the two effects through the amount of SA, the release modifiability of drug delivery systems has been greatly enhanced. This study could significantly enhance the tunability of hydrogel drug delivery systems.