Effect of AgNPs on cell survival. Dose-dependent effects of AgNPs on bacterial survival. All test strains were incubated in the presence of different concentrations of AgNPs. Bacterial survival was determined at 4 h by a CFU assay. The results are expressed as the means ± SD of three separate experiments each of which contained three replicates. Treated groups showed statistically significant differences from the control group by the Student's t test (p < 0.05).