Combined biological effects of silver nanoparticles and heavy metals in different target cell lines

Silver nanoparticles (AgNPs) and heavy metals are considered to coexist in the environment. Increasing evidence shows that AgNPs can interact with heavy metals; however, the impact of distinct exposure conditions on their combined toxicity is still largely unknown. Here, we investigated the co-effects of AgNPs and heavy metals, including arsenic (As), cadmium (Cd), and nickel (Ni), in target cell lines. The results demonstrated that pretreated with polyvinylpyrrolidone-coated (PVP-coated) AgNPs at noncytotoxic concentrations significantly inhibited the cytotoxicity of As and Cd in human-hamster hybrid A_L cells, but had slight effect on the toxicity of Ni. The antagonistic effects have also been observed in other non-cancerous cell lines, such as Chinese hamster ovary (CHO) cells, mouse embryonic fibroblasts (MEFs), and human normal liver (LO₂) cells. In addition, the co-effects between AgNPs and heavy metals are independent of surface coatings of AgNPs. Our data revealed that the combined biological effects of AgNPs and heavy metals are closely related to the physicochemical properties of heavy metals themselves and the tested cell lines.