Bactericidal effect of starch-stabilized zero-valent iron nanoparticles on Escherichia coli

Aims: The present study reports the antibacterial efficiency of starch-stabilized nano scale zero-valent iron (S-NZVI) particles on Escherichia coli. Materials and Methods: NZVI was synthesized using NaBH 4 and FeSO 4 .7H 2 O, and characterized by scanning electron microscopy, as well as X-ray diffraction. The effects of concentration, contact time, dissolved oxygen, and stabilization were tested. E. coli was determined by the pour plate method. Results: The results revealed that the complete inactivation (100%) of E. coli was occurred at using 100 mg/l of NZVI after 30 min under anaerobic condition. The inactivation efficiency was decreased in an aerobic condition. When NZVI concentration increased to 500 and 1000 mg/L, complete inactivation was achieved under both anaerobic and aerobic condition. In general, E. coli inactivation efficiency using NZVI was strongly dependent on the contact time and the concentration of NZVI particles with its maximum efficiency at 500 mg/L within 120 min. Stabilization-NZVI by starch did not improve its bactericidal activity and the inactivation of E. coli by stabilized nanoparticles required higher concentration compared to that by nonstabilized nanoparticles. Conclusion: The present study showed that nonstabilized Fe 0 nanoparticles have higher bactericidal efficiency than that of S-NZVI. This investigation also suggests that NZVI can be used as an effective and strong agent for antimicrobial applications.