Cytotoxicity of serum protein-adsorbed visible-light photocatalytic Ag/AgBr/TiO2 nanoparticles

Highlights: ► Photocytotoxicity of visible-light catalytic NPs was examined in vitro. ► Ag/AgBr/TiO2 NPs were well internalized in cells after adsorption of serum proteins. ► Cell viability was decreased by 40–60% using ∼8 ppm NPs and 60 W/cm2 visible light within 5 h. ► Mitochondria activity test indicated the reactive oxygen species for photo-destruction of cells. ► Ag/AgBr/TiO2 NPs were found to eliminate xenograft tumors significantly in vivo. - Abstract: Photocytotoxicity of visible-light catalytic Ag/AgBr/TiO2 nanoparticles (NPs) was examined both in vitro and in vivo. The Ag/AgBr/TiO2 NPs were prepared by the deposition–precipitation method. Their crystalline structures, atomic compositions, and light absorption property were examined by X-ray diffraction (XRD) patterns, X-ray photoelectron (XPS) intensities, and ultraviolet-visible (UV–vis) diffuse reflectance spectroscopic tools. The Ag/AgBr/TiO2 NPs appeared to be well internalized in human carcinoma cells as evidenced by transmission electron microscopy (TEM). The cytotoxicity of cetylmethylammonium bromide (CTAB) appeared to be significantly reduced by adsorption of serum proteins in the cellular medium on the NP surfaces. Two types of human cervical HeLa and skin A431 cancer cells were tested to check their viability after the cellular uptake of the Ag/AgBr/TiO2 NPs and subsequent exposure to an illumination of visible light from a 60 W/cm2 halogen lamp. Fluorescence images taken to label mitochondria activity suggest that the reactive oxygen species should trigger the photo-destruction of cancer cells. After applying the halogen light illumination for 50–250 min and ∼8 ppm (μg/mL) of photocatalytic Ag/AgBr/TiO2 NPs, we observed a 40–60% selective decrease of cell viability. Ag/AgBr/TiO2 NPs were found to eliminate xenograft tumors significantly by irradiating visible light in vivo for 10 min.