Harnessing blue light: ZnO-HAP composite for antimicrobial oral care and enamel restoration

Photocatalytic materials have shown great potential in oral care for caries prevention. However, challenges remain in promoting enamel remineralization while ensuring biosafety, as photocatalytic agents are applied directly to the tooth surface and may contact oral tissues or be swallowed. This study aimed to design a multifunctional photocatalytic material that integrates antibacterial, and remineralizing properties with high biosafety.

A hydroxyapatite-zinc oxide (ZnO-HAP) composite was synthesized via a hydrothermal method and characterized by XRD, SEM, and EDS. Photocatalytic activity under blue light (455 nm) was evaluated through hydroxyl radical (·OH) generation and dye degradation. Antibacterial, and remineralization performances were evaluated using standard plate counting method, and Vickers method. Biosafety was examined through cell viability assays and in vivo tests in mice.

The ZnO-HAP composite exhibited strong photocatalytic activity and generated abundant hydroxyl radicals under blue light irradiation. ZnO-HAP treatment under light irradiation resulted in superior antibacterial efficacy and minimal enamel damage. The Ca/P ratio on the enamel surface increased from 1.52 to 1.86 after treatment, indicating effective mineral restoration. Moreover, the ZnO-HAP composite demonstrated excellent cytocompatibility, suggesting good biosafety.

The ZnO-HAP composite combines antibacterial activity, and remineralization capability in a biocompatible platform. Its biomimetic composition and light-activated functionality offer a safe and effective strategy for comprehensive oral care and enamel regeneration.