pH-responsive hydrogel microspheres for efficient antibacterial activity

According to the Global Burden of Disease Study 2017, nearly half of the world's population suffers from oral diseases, putting great pressure on the social economy and population health. However, the continuous use of chlorhexidine (CHX), the main drug for oral diseases, often leads to adverse reactions, such as tooth staining and taste disturbance. Moreover, residence time in the mouth is short, indicating little effect. Based on the pH difference between the patients' healthy and pathological tissues, in this study, we designed a pH-sensitive hydrogel sustained-release system. First, citraconic anhydride-chitosan (CAS) was synthesized from chitosan (CS) and citraconic anhydride. Then, we used it as a carrier to load the CHX. Nuclear magnetic resonance hydrogen spectrum analysis, rheological experiments, and mechanical tests were used to demonstrate that the CAS composite hydrogel was successfully synthesized. In addition, in vitro drug release studies confirmed that the CHX was released from hydrogel differently in acidic and basic environments. Moreover, we verified that it had suitable biocompatibility and antibacterial activity through cytotoxicity and antibacterial experiments. This study is of great significance for improving the treatment of oral diseases in clinical settings and also provides new ideas for drug release in other acidic pathological environments.