In vivo biodistribution and synergistic toxicity of silica nanoparticles and cadmium chloride in mice

Silica nanoparticles (SiNPs) are now in daily use due to their low intrinsic toxicity. Cadmium is a ubiquitous environmental pollutant. In spite of real risk of humans' co-exposure to SiNPs and cadmium, their synergistic toxicity is still unclear. Here, we report the synergistic effects of SiNPs and CdCl2 on their biodistribution and subacute toxicity in mice. The biodistributions, histopathological changes, serum biochemical parameters and oxidative stress responses were determined after intraperitoneal injection of SiNPs and/or CdCl2 to mice. SiNPs and CdCl2 have a positive synergistic toxicity in mice. Although SiNPs were low toxic to mice, co-exposure of SiNPs and CdCl2 significantly enhanced CdCl2-induced oxidative damage in the liver as indicated by the severe liver dysfunction and histopathological abnormalities. Co-exposure to SiNPs and CdCl2 markedly increased the cadmium accumulation in the liver, which induced significant hepatic oxidative stress. In vitro binding assays indicated that serum albumin and Cd2+ mutually enhanced the binding of each other to SiNPs via the interaction of serum albumin and Cd2+. The uptake of serum albumin- and Cd2+-bound SiNPs by the macrophages significantly increased cadmium accumulation in mice. These results demonstrate that serum albumins play an important role in the positive synergistic toxicity of SiNPs and CdCl2. (C) 2013 Elsevier B.V. All rights reserved.