Figure 4.

(a) Viability of L929 cells exposed to silver (AgNPs) and gold nanoparticles (AuNPs) stabilized with cysteine (CYS) or glutathione (GSH), Ag⁺ and Au³⁺ ions during 24 h and determined by the MTT cytotoxicity assay. (b) The effect of AgNPs, AuNPs, Ag⁺, and Au³⁺ on the number of live (white columns), early apoptotic (dotted columns) and late apoptotic (blue columns) L929 cells after 24 h exposure, determined by flow cytometry after Annexin V/PI staining. (c) The effect of AgNPs, AuNPs, Ag⁺, and Au³⁺ on the level of peroxy radical (white columns, as measured by DCFH-DA assay) and total GSH (blue columns, as measured by MBCl assay) in L929 cells after 4 h of exposure. Negative controls (neg) were untreated cells. Positive controls (pos) were cells treated with DMSO for MTT and Annexin V/PI assays, or with the t-butylhydroxyde for DCFH and MBCl assays. The results are expressed as percentage of negative controls and given as mean values obtained from three independent experiments. Standard deviations are presented as scale bars. Values marked with asterisk (*) differ significantly from the negative control (P < 0.05).