With the rapid increase of multiple drug-resistant bacteria, silver nanoparticles (AgNPs) with
broad-spectrum antibacterial activities have been widely applied in the treatment of bacterial infection.
Meanwhile, AgNPs also have anticancer activities against different cell lines. The toxic effects of
AgNPs depend on concentration, size, shape, coated materials and surrounding environments. In order
to better understand the antibacterial and antitumor effects of AgNPs, various investigations have been
carried out to uncover the molecular mechanism of action. This review summarizes the recent studies on
the action mechanisms of AgNPs related to their antibacterial activities including collapsing cell walls,
inducing reactive oxygen species, inhibiting aerobic respiration and damaging DNA and their antitumor
effects including impairing mitochondria, blocking cell cycle, and activating apoptosis. In these investigations,
the systematic approaches have not been extensively applied. Increasingly matured omics techniques
including genomics, transcriptomic, translatomics and proteomics should be more widely explored
to provide the comprehensive views of the cytotoxic effects of AgNPs to bacteria and tumor cells
and thus globally illustrate the molecular mechanisms of the cytotoxicity, promoting the better medical
application of AgNPs in the future.