Nitrogen-doped carbon dots as a highly efficient photosensitizer for photodynamic therapy to promote apoptosis in oral squamous cell carcinoma

Abstract

Photodynamic (PDT) is a new strategy for non-invasive tumor therapy and has been studied for the treatment of oral cancer. PDT has the advantages of low damage and high therapeutic efficiency. However, conventional photosensitizers have defects in different degrees, such as low stability and solubility, and low oxygen quantum yield of singlet oxygen. These defects greatly limit the efficiency of PDT. Several studies have shown that carbonaceous nanomaterials, carbon dots (CDs), are promising as a novel nanoscale photosensitizer to mediate PDT for cancer treatment. In this study, we utilized fluorescent CDs doped with nitrogen to optimize their photosensitizing activity to enhance PDT in oral squamous cell carcinoma (OSCC). Nitrogen-doped CDs were able to generate a large amount of reactive oxygen species (ROS) under 660-nm laser irradiation after uptake by cancer cells, effectively inducing apoptosis in the mitochondrial pathway. The in vivo and in vivo experiments verified that CDs-mediated PDT was able to promote apoptosis of tumor cells in terms of DNA damage, inhibition of angiogenesis and cell proliferation, etc. CDs, as a novel photosensitizer, is expected to be an outstanding tool for clinical PDT in the treatment of OSCC.