pH-triggered chitosan-sodium caseinate nanocarriers with charge-switching property: Characterization and applications in dental care

As a typical biofilm disease, dental caries is a public healthcare problem and high sugar diets increase the risk of dental caries. Cationic nanomaterials play an important role in targeting and removing of biofilms, but their negative effects on normal cells have always caused widespread concern. In this work, pH-triggered charge-switching nanoparticles (SC&CS NPs) with selectable targeting were skillfully constructed by electrostatic adsorption and chemical cross-linking of sodium caseinate (SC) and chitosan (CS) to develop functional foods. SC&CS NPs were negatively charged and stable at pH 7.4. Once encountering in acidic microenvironment below pH 5.7, the potential of SC&CS NPs converted to positive. Based on this property, SC&CS NPs could identify the infected sites of biofilms to selectively target bacteria, while not interacting with cells in the normal physiological environment, thereby avoiding damage to normal cells. Besides, SC&CS NPs were excellent delivery systems that could effectively encapsulate bioactive ingredients with high loading efficiency (12.16 ± 0.04%) and release bioactive ingredients on demand. Moreover, after being encapsulated by SC&CS NPs, the antibacterial and anti-biofilm activities of bioactive ingredients were significantly improved. The charge-switching nanomaterials are expected to provide a safer, more effective, and smarter strategy for functional foods.