Abstract
The current research reports the antibacterial effects of silver (Ag) and citric acid coated iron oxide (Fe3O4) NPs on Escherichia coli wild type and kanamycin-resistant strains, as well as on Salmonella typhimurium MDC1759. NPs demonstrated significant antibacterial activity against these bacteria, but antibacterial effect of Ag NPs is more pronounced at low concentrations. Ag NPs inhibited 60–90% of S. typhimurium and drug-resistant E. coli. The latter is more sensitive to Fe3O4 NPs than wild type strain: the number of bacterial colonies is decreased ~ 4-fold. To explain possible mechanisms of NPs action, H+-fluxes through the bacterial membrane and the H+-translocating FOF1-ATPase activity of bacterial membrane vesicles were studied. N,N′-Dicyclohexylcarbodiimide (DCCD)-sensitive ATPase activity was increased up to ~ 1.5-fold in the presence of Fe3O4 NPs. ATPase activity was not detected by Ag NPs even in the presence of DCCD, which confirms the bactericidal effect of these NPs. The H+-fluxes were changed by NPs and by addition of DCCD. H2 yield was inhibited by NPs; the inhibition by Ag NPs is stronger than by Fe3O4 NPs. NPs showed antibacterial effect in bacteria studied in concentration-dependent manner by changing in membrane permeability and membrane-bound enzyme activity. The FOF1-ATPase is suggested might be a target for NPs.
Highlights
The current research reports the antibacterial effects of silver (Ag) and citric acid coated iron oxide (Fe3O4) NPs on Escherichia coli wild type and kanamycin-resistant strains, as well as on Salmonella typhimurium MDC1759
Our results showed that the Fe3O4 NPs demonstrate different effects on Gram-negative and Gram-positive bacteria
It is important to study the effect of Ag and F e3O4 NPs on E. coli wild type and antibiotic-resistant strains, as well as S. typhimurium MDC1759 strain, for revealing the action mechanisms
Summary
The current research reports the antibacterial effects of silver (Ag) and citric acid coated iron oxide (Fe3O4) NPs on Escherichia coli wild type and kanamycin-resistant strains, as well as on Salmonella typhimurium MDC1759. Ag NPs inhibited 60–90% of S. typhimurium and drug-resistant E. coli The latter is more sensitive to Fe3O4 NPs than wild type strain: the number of bacterial colonies is decreased ~ 4-fold. Iron oxide NPs such as Fe3O4 and γ-Fe2O3 NPs due to their super paramagnetic, high magnetic susceptibility and other properties are promising agents for biomedical applications. Nowadays, they have been used in drug delivery systems to deliver various compounds such as peptides, DNA molecules, chemotherapeutic, and hyperthermic drugs[1,17,18]. Magnetic targeting of drug delivery is considered as the most efficient w ay[17]
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