Antibacterial activities of transient metals nanoparticles and membranous mechanisms of action.

Various transient metal and metal oxide nanoparticles (NPs) have shown pronounced biological activity, including antibacterial action against different Gram-negative and Gram-positive bacteria including pathogens and drug-resistant ones. Thus, NPs can be applied in nanotechnology for controlling bacterial growth as well as in biomedicine for the treatment of various diseases. However, the mechanisms of these effects are not clear yet. This review is focused on the antibacterial effects of transient metal NPs, especially iron oxide (Fe3O4) and Ag NPs on Escherichia coli wild type and antibiotic-resistant strains. Ag NPs show more pronounced bactericidal effect than Fe3O4 NPs. Moreover, Ag NPs display more expressed antibacterial effect at low concentrations. Interestingly, kanamycin-resistant strain is more susceptible to Fe3O4 NPs than wild type strain. In order to explain the possible mechanisms of NP effects, in addition to the production of reactive oxygen species causing damage in cells, particularly, their membranes, the changes in the membrane-associated H+-translocating FOF1-ATPase activity, H+-fluxes through the bacterial membrane, redox potential and hydrogen yield by membrane-associated enzymes-hydrogenases, are discussed. We observed from the results that FOF1-ATPase could be a main target for NPs. A scheme of possible action mechanism is proposed.