Oxidative stress following exposure to silver and gold nanoparticles in mice

Silver (Ag) and gold nanoparticles (Au NPs) have wide applications. They are increasingly being used in the medical devices, biosensors, cancer cell imaging, and cosmetics. Increased applications of these NPs in the technological advances have also led to the risk of exposure to these particles. This study investigated the toxic effects of Ag and Au NPs (1 μM and 2 μM, oral) on mouse erythrocytes and tissues after 14 consecutive days' exposure. Our results demonstrate significant increase in reactive oxygen species (ROS) and depletion of antioxidant enzyme status in erythrocytes and tissues. Hepatic and renal toxicity was evident from liver and kidney function tests. Inflammatory markers, interleukin-6 and nitric oxide synthase increased in plasma on administration following exposure to these NPs at both the doses. A more pronounced increase was noted in kidney metallothionein (MT) compared to liver MT on exposure to these NPs. Toxic potential of these NPs was further confirmed by increased 8-hydroxy-2'-deoxyguanosine levels in urine, a biomarker of DNA damage. Among the two NPs, Ag NP was more toxic at 2 μM dose compared to lower dose of 1 μM. The study suggests oxidative stress as the major mechanism responsible for the toxic manifestations induced by Ag and Au NPs.