Laser-activated NGQDs boost the therapeutic response of 5-FU in breast cancer cells.

The development of efficient therapeutic approaches for cancer has attracted much attention. Photodynamic therapy combines photosensitizer materials with a laser to enhance ROS production at the tumor site, leading to cancer cell apoptosis. This study investigates the role of nitrogen-doped graphene quantum dots (NGQDs) in enhancing the therapeutic efficacy of 5-fluorouracil (5-FU) in MDA-MB-231 cells under 660 nm diode laser irradiation with 100 mW Laser power. A cytotoxicity assay was used to define the optimized NGQD concentration. Then, the effect of NGQD combinations with 5-FU and 660 nm irradiation on ROS generation and the SOD and catalase activities was measured. To clarify the mechanisms of ROS production, a comprehensive analysis was conducted on various nitrogen configurations within the GQD structure. Also, the influence of spin-orbit coupling (SOC) between the doped electrons and the band structure of graphene, with a particular focus on the K and K' points, was investigated. The MTT assay indicated that the combination of NGQD with 5-FU and laser effectively reduced the dosage of 5-FU treatment. Furthermore, NGQD elevated levels of ROS generation by inhibiting the SOD and CAT activity after the laser irradiations. Results showed increased sensitivity of the MDA-MB-231 cells to the 5-FU and decreased ability to maintain redox equilibrium. These findings highlight the crucial role of NGQDs in facilitating triplet state formation and robust ROS generation, ultimately potentiating 5-FU's anticancer efficacy and paving the way for innovative combinational therapies.