Abstract: Objective To investigate the anti-tumor effect of BSA@CuS-PEG nanocomposites on tongue squamous cell carcinoma. Methods Transmission electron microscopy, dynamic light scattering, Zeta potential and ultraviolet absorption spectroscopy were used to characterize the synthesized BSA@CuS-PEG nanocomposite, whose photothermal properties was assessed with near infrared II region excitation light (1064 nm). The cytotoxicity of the nanocomposite in Cal27 and SCC9 cells was evaluated using CCK-8 assay, and its effect on cell cycle distribution was analyzed using flow cytometry. The in vivo antitumor effect of BSA@CuS-PEG was investigated in a Balb/c mouse model bearing subcutaneous Cal27 tumor xenograft. Results The synthesized BSA@CuS-PEG nanocomposite showed a temperature variation (ΔT) of about 30 ℃ under near-infrared (NIR) irradiation (0.5 W/cm2), suggesting its excellent photothermal sensitivity. CCK-8 assay showed that BSA@CuS-PEG had no significant toxicity to tumor cells, but upon NIR irradiation, the nanocomposite produced a significant stronger inhibitory effect on Cal27 and SCC9 cells than free nanocomposites (P<0.001). Cell cycle analysis showed that compared with free nanocomposites, BSA@CuS-PEG plus NIR irradiation caused more obvious cell cycle arrest at G2/M phase in tongue cancer cells (P<0.001). In the tumor-bearing mice, BSA@CuS-PEG combined with NIR irradiation produced a significant anti-tumor effect as compared with saline treatment plus NIR irradiation (P<0.001). Conclusion The BSA@CuS-PEG nanocomposite shows prominent photothermal properties and good anti-tumor effects both in vivo and in vitro, and thus provides a promising method for non-invasive early diagnosis and non-surgical treatment of primary tongue cancer.

Key words: photothermal therapy; copper sulfide; tongue cancer; nanocomposites