The Journal of

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Introduction: Introducing a powerful antibacterial agent to control pathogenic bacteria especially strains resistant to antibiotics is of paramount importance. The purpose of this study is ZnO nanoparticles synthesis by using ultrasonic waves and evaluation of its antibacterial properties. Methods: Zinc oxide nanoparticles were synthesized using ultrasound irradiation. Then physical and chemical properties of nanoparticles were studied. Antibacterial activity of the nanoparticles was investigated for two strains bacteria: Escherichia coli and Staphylococcus aureus through standard methods such as placing well and disc diffusions, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Results: Chemical and physical investigation of the synthesized ZnO nanoparticles indicated that from nanoscale particles, spherical forms were produced with no impurities. The MIC for E.coli and Staph.aureus were reported as 0.125 mg/ml, and 0.062 mg/ml respectively. The MBC for E.coli and Staph. aureus was reported to be 0.500 mg/ml, and 0.250 mg/ml respectively. In comparison, for the methods of well and disc diffusions, inhibition zone diameter of the well method was more than disc diffusion. Conclusion: High purity zinc oxide nanoparticles can be synthesized by ultrasonic waves and have the significant antibacterial properties against Escherichia coli and Staphylococcus bacteria. In contrast to Escherichia coli, Staph. aureus showed greater sensitivity against Zinc Oxide nanoparticles.

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Introduction: Increasing resistance to antimicrobial agents is typically one of the main problems of health care. Control the dispersion of bacteria in different environments is a challenge in this section that to the overcome of them is essential for health and economic. In this study, nano-silver antibacterial activity was studied against Gram-positive bacteria Staphylococcus aureus and Pseudomonas aeruginosa and Gram-negative bacterium E. coli and Bacillus cereus.

Methods: Anti-bacterial properties of silver nanoparticles against bacteria were assessed using dilution method. Bacteriological tests were performed using the initial concentration of (1 -1.5× 10-5) CFU / ml of each type of bacteria. The minimum inhibitory concentration (MIC) of growth and minimum bactericidal concentration (MBC) was determined for each bacteria in the agar medium. Since the death of bacteria was studied using a double-MIC concentrations in duration of zero to 540 min and was determined the death time of each bacteria.

Results:The results showed that MIC for bacteria of E. coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa was at a concentration of 1700, 1600, 1500, and 1600 microgram per liter of silver nanoparticles, respectively. Also, the lowest death time was obtained 4h, for Bacillus cereus bacteria.

Conclusion: Based on the results of this study, bacteria E. coli showed the lowest sensitivity and Staphylococcus aureus the greatest sensitivity to silver nanoparticles.