Cytotoxicity of silver nanoparticles

Abstract

Nanosilver is a one of the most common engineered nanomaterials in textiles, food packaging, paints and air or water filters demanding a better understanding of its toxicity. Here, the viability of murine macrophages (RAW 264.7) was investigated in the presence of nanosilver using a MTS assay. The nanosilver was immobilized on nanostructured silica to prevent its flocculation during cytotoxicity evaluation. Cell cultures were exposed to 0-490 mg/L of pure silica and Ag/SiO 2 nanoparticles containing 50 wt% Ag. The average Ag nanoparticle diameter was closely controlled from 5.7 to 16.8 nm at an Ag mass concentration of 5, 10 and 20 mg/L over 26 h. Nanostructured silica was non-toxic at concentrations below 50 mg/L. Cell viability depended on both Ag size and concentration. The cytotoxicity was dominated by the release of silver ions from the surface of the smaller nanosilver particles. For larger ones, the released ions and the direct contact of cells with the nanosilver surface played a comparable role. Size dependent differences in the cytotoxicity of nanosilver were further confirmed by dark field imaging. Nanosilver was less toxic to murine macrophages than to E. coli bacteria at similar concentrations and particle sizes.