Reactive Oxygen Species-Mediated Oral Cancer Cells Treatment Using Photosensitizer-Combined Carbon Dots via Apoptosis–Ferroptosis Synergistic Therapy

In this study, the applicability of carbon dots (CDs) for the treatment of oral cancer cells in vitro was assessed under laser irradiation. For the study, CDs were synthesized using an amino acid via heat treatment and then combined with a photosensitizer. The absorbance and photoluminescence of CDs were measured. The production of reactive oxygen species (ROS) was evaluated using assay agents. The glutathione (GSH) content of the test solutions was evaluated. The viability of normal and cancer cells was evaluated using CDs at different concentrations under laser irradiation. Live/dead cells and intracellular lipid peroxidation (LPO) were observed after treatment. According to the assays, the production of •OH, •O2−, and 1O2 was spectroscopically observed, which was reflected by the change in their peak absorbance. GSH was depleted mostly during light irradiation. Cancer cells were eliminated without leaving visible live cells, whereas normal cells were minimally affected. Intracellular LPO was confirmed in cells by green fluorescence, which was emitted from an oxidized assay dye. Conclusively, the amino acid-based photosensitizer-combined CDs eliminated approximately 70% of the cancer cells in vitro under laser irradiation, with no visible live cells. Based on these assays, ROS production may induce cell death via synergistic apoptosis–ferroptosis therapy.