Investigating of antimicrobial efficiency of starch-stabilized zero-valent iron nanoparticles on Escherichia coli

Abstract

Introduction: Stabilized nano zero valent iron (NZVI( particles have potential for in-situ environmental remediation. However, little is known regarding the impact of these nanoparticles on microorganisms. The present study compared antibacterial effect of bare Nano scale Zero Valent Iron (NZVI) particles and stabilized nanoparticles with 0.2 % (w/w) starch on E.coli as a model microorganism. Material and method: The non-stabilized and starch stabilized nano- scale zerovalent iron particles were synthesized via aqueous phase reduction of ferrous sulfate by sodium borohydride. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the synthesized nanoparticles. E.coli was determined by the pour plate method. The statistical analyses were performed using Minitab16 and four way Analysis of Variance. Result: According to XRD analysis and SEM image, the synthesized crystals were about 50 to 100 nm and there were no impurities in the crystal nanoparticles. Results revealed that inactivation efficiency strongly depended on contact time and NZVIPs concentration with maximum efficiency at 500 and 1000 mg/l (100%). By increasing contact time, required concentration of nanoparticles decreased. Stabilization of NZVI by starch didn’t improve its bactericidal activity. The inactivation efficiency was decreased in aerobic condition. Conclusion: Stabilization of nanoparticles with 0.2 % (w/w) starch not only increased inactivation of bacteria but also decreased the rate of E.coli inactivation. In general, the highest efficiency was resulted by using 500 and 1000 mg/l of none stabilized NZVI under anaerobic condition.