Antibacterial coatings have been utilized in clinical, industrial and even home uses to prevent associated infections [1-2]. In the present work, the synthesis of ZnO nanoparticle as an antibacterial substance has been carried out by the aim of the sonication method in a simple and fast way. The synthesized ZnO nanoparticles have been characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results confirmed that the ZnO is pure and the average particle size is 27nm. The resulting nanoparticles have been deposited on the steel surface in the presence of ultrasound as ultrasonic irradiation is an effective method for deposition and adhesion of nanoparticles on various surfaces. Antibacterial properties of ZnO nanoparticles have been evaluated by absorbance method. The ZnO nanoparticles were dispersed in glycerol with the help of ammonium citrate as dispersant. The antibacterial tests were performed by measuring the optical density of E. coli O157:H7 in tryptic soy broth (TSB) medium in the presence of the resulting ZnO nanofluid containing different concentrations of ZnO nanoparticles. The results showed that ZnO nanoparticles have antibacterial activity against E. coli O157:H7 and the inhibitory effect increases with increasing nanoparticle concentration. The minimum inhibitory concentration (MIC) value against E. coli O157:H7 was found to be 1.5 mg ml−1. The antibacterial activity of steel coated with ZnO nanoparticles against E. coli O157:H7 has been investigated by colony count method. Survival ratio of bacteria decreases in the presence of ZnO-coated steel. Our results confirmed that the resulting surfaces can be useful for antibacterial purposes.

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