Stress Response of Gram-Positive and Gram-Negative Bacteria Induced by Metal and Non-metal Nanoparticles. In Search of Smart Antimicrobial Agents

Abstract

The increasing resistance of pathogens to a number of antibiotics has been the subject of many research reports from the European Antibiotic Resistance Surveillance Network (Ears-Net) and The World Health Organization (The WHO). The aim of this work was to study the effects of nanomaterial dispersions as Selenium (Se), Gold (Au), Iron oxide (Fe2O3), Silicon dioxide (SiO2) and Graphene oxide (GO) on bacteria like Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and two strains of Escherichia coli. Two classical methods were used to investigate the antibacterial effect of the nanoparticles (NPs): Spot and Well diffusion tests in agar medium. The tested nanoparticles were active against Gram-positive bacteria in concentrations between 3.0 and 1.5 mg/mL but they were not active against Gram-negative bacteria such as E. coli. Among tested nanomaterials, SeNPs express the strongest antimicrobial effect. Gold nanoparticles with Polyvinylpyrolidone (Au-PVP NPs) were more active against bacteria than pure AuNPs. Lower concentrations (1.0 mg/mL and 0.5 mg/mL) of Se, GO and the two types of Gold nanoparticles did not show activity against all test microorganisms. Fe2O3 NPs as well as SiO2 NPs had no effect on any test bacteria in the mentioned concentrations. In conclusion, the most cytotoxic for tested bacteria were SeNPs, followed by Au-PVP and AuNPs. GONPs also showed a certain cytotoxic effect, especially on B. cereus 1095.