▎ 摘　　要

As a promising next-generation photodynamic therapy (PDT) photosensitizer, TiO2 nanoparticles (NPs) has gained great attention due to its higher efficiency. Yet, its application in PDT is strongly limited by its UV light response range. In this work, TiO2 NPs conjugated with reduced graphene oxide (RGO-TiO2) composites were successfully prepared by hydrothermal reduction method. They were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). Superior adsorption and killing efficiency under UV-A light or visible light were achieved in the presence of the RGO rather than that of unmodified TiO2. The optimal photocatalytic activity was obtained when modified proportion was 0.2 (RGO:TiO2). Dark cytotoxicity was observed using 0-500 mu g mL(-1) RGO-TiO2 during long incubation time. In parallel, following exposure of human hepatocellular carcinoma cell line (HepG2 cells) to RGO-TiO2 and UV-A or visible light irradiation, a marked decrease in the ratio of the super-coiled DNA, mitochondrial membrane potential (MMP), and the oxidative damage effects, as well as increased the apoptosis rate and intracellular calcium concentration were observed. Moreover, photocatalytic RGO-TiO2 composites killed the HepG2 cells by apoptosis pathway. The results suggested that RGO-TiO2 composites were an excellent candidate as a PDT photo sensitizer in the near future.