Sulphur-doped carbon dots as a highly efficient nano-photodynamic agent against oral squamous cell carcinoma.

OBJECTIVES: Photodynamic therapy (PDT) is a novel non-invasive therapeutic method, which has been widely applied for the treatment of human oral cancers. However, the problems of undesirable singlet oxygen ((1) O2 ) quantum yields and long-term phototoxicity were inevitable during the application of traditional photosensitizers. Therefore, it is necessary to explore novel photosensitizers for the improvement of therapeutic effects. In our study, the sulphur-doped carbon dots (S-CDs) of high yield of singlet oxygen ((1) O2 ) were synthesized as a nano-photosensitizer for OSCC to improve the PDT efficacy in clinical practice. MATERIALS AND METHODS: After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen ((1) O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated. RESULTS: After synthesis of the novel S-CDs, the size, morphologic characteristics, surface potential and yield of singlet oxygen ((1) O2 ) were determined. In vitro study was performed to compare the therapeutic effect as well as the biocompatibility of the novel S-CDs to those of 5-ALA. Besides, possible mechanism of action was illustrated. CONCLUSIONS: These data from the in vitro study demonstrated the promising safety profile of the low dose (nmol/L) S-CDs, which indicated the novel S-CDs could be used as a promising photodynamic agent for oral cancer therapy.