Neoplastic cell response to tiopronin-coated gold nanoparticles.

The present study characterized the in vitro biological response of a comprehensive set of cancer cell lines to gold nanoparticles (2.7 nm) coated with tiopronin (AuNPs-TP). Our findings suggest that upon entering cells, the AuNPs-TP are sequestered in vacuoles such as endosomes and lysosomes, and mostly localize in perinuclear areas. Peak cell accumulation was achieved at 8 hours after incubation. L929 and H520 cells showed more than 75% surviving fraction when treated with 0.5 mg/mL of AuNPs-TP for 24 hours, whereas the surviving fractions were 60% in MCF-7 and 20% in HeLa cells. Reactive oxygen species (ROS) production by the AuNPs-TP was dependent on cell line and exposure time. Antioxidants inhibited ROS generation to various extents, with glutathione and tiopronin being most effective. Overall, exposure time, concentration of the AuNPs-TP, and cell line influenced neoplastic cell response. Furthermore, the mechanism of cytotoxicity of the AuNPs-TP was found to be ROS generation. This study describes the basic intracellular characteristics of Tiopronin-Au nanoparticles from the standpoint of their anti-cancer activity in different cancer cell cultures.