Host Immune Response Triggered by Graphene Quantum-Dot-Mediated Photodynamic Therapy for Oral Squamous Cell Carcinoma

INTRODUCTION: With the innovation of photosensitizers, photodynamic therapy is now widely used in antitumor detection and treatment. Graphene quantum dots (GQDs) are proposed as a promising alternative photosensitizer due to their high biocompatibility, specific photoactivity, and strong tumor concentration. However, the changes in host immunity triggered by GQDs have only rarely been reported. METHODS: In this work, GQDs as photosensitizers were conjugated to polyethylene glycol (PEG) to enhance solubility and blood circulation. The phototoxicity of the resulting GQD-PEG nanomaterials was then detected in vitro and in vivo. The antitumor immunity triggered by GQD-PEG under irradiation was further evaluated in an oral squamous cell carcinoma animal model. RESULTS: The obtained GQD-PEG nanomaterials exhibited low cytotoxicity, good solution stability, and excellent endocytosis. Both in vitro and in vivo, all demonstrated strong ablation for oral squamous cell carcinoma under irradiation. Meanwhile, host-immunity-related CD8(+) T cells (cytotoxic T lymphocytes) and proinflammatory cytokines, including IFN-γ and TNF-α, were significantly increased after photo-activated antitumor activity. CONCLUSION: These results highlight the dominant role of GQD-PEG in photodynamic therapy and could have significant implications for further combination therapy as a promising antitumor immune response strategy triggered by nanomaterials.