Enhanced antibacterial properties of the bracket under natural light via decoration with ZnO/carbon quantum dots composite coating

Highlights: • Originally construct ZnO/CQDs antibacterial coating on the bracket. • The preparation method is facile, low-cost and environmentally friendly. • The bracket modified via the ZnO/CQDs coating exhibits high antibacterial ability. • The bracket can make full use of the natural light to kill bacteria. • The transparent coating ensure the texture and aesthetics of the bracket. Enamel demineralization of the brackets caused by surrounding bacteria is the main challenge facing orthodontists. Aiming to resolve this issue, here we originally reported a novel antibacterial coating based on ZnO and carbon quantum dots (CQDs) composite prepared via a facile and environmentally-friendly method. As desired, the bracket modified with ZnO/CQDs coating exhibited excellent antibacterial performance than the unmodified bracket (Streptococcus mutans 96.13%, Staphylococcus aureus 90.28% and Escherichia coli 92.35%) under natural light. In addition, the natural light antibacterial mechanism was explored, which could be ascribed to the upconversion fluorescence of the CQDs and the interaction between CQDs and ZnO.