Tehran University Medical Journal

Background: Nanoparticles are particles that have at least one dimension between 1 and 100 nanometers. Nanoparticles are a new generation of antimicrobial agents. Nanoparticles with antimicrobial activity, especially as a new class of biomedical materials for use in increasing the level of public health in daily life have emerged.  Zinc oxide nanoparticles have attracted a great attention due to the variety of their applications in medical science. The aim of this study was to evaluate and compare the antimicrobial activity of zinc oxide nanoparticles synthesized by green method.
Methods: This experimental study was done in 2017, from March to September in the Bam Research Center of University of Medical Sciences Kerman, Iran. Green synthesis of zinc oxide nanoparticles was investigated using cumin seeds. The physicochemical characteristics of synthesized nanoparticles were studied by UV-visible ultraviolet spectrometer (Analytik Jena AG, Germany), X-ray diffraction and transmission electron microscope (TEM) (Carl Zeiss, Germany). Broth microdilution method was used to investigate the antimicrobial activity of zinc oxide nanoparticles. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these nanoparticles were determined for Pseudomonas aerogenes and Enterococcus faecalis strains.
Results: The UV-visible ultraviolet spectroscopy showed an absorption peak in the range of 370 nm. Transmission electron microscopy shows the synthesis of zinc oxide nanoparticles, mostly spherical, with a size less than 50 nm. Minimum inhibitory concentration of zinc oxide nanoparticles against P. aerogenes and E. faecalis strains was determined at 6.25 and 12.5 μg/ml, respectively. Both bacteria were sensitive to zinc oxide nanoparticles. This sensitivity was higher for gram-negative bacteria.
Conclusion: Zinc oxide nanoparticles were produced using Iranian natural resources and our results showed significant antibacterial activity. Nanotechnology creates materials with novel properties every day, and creates new hope for improving environmental pollution. These nanoparticles can be used as a new generation of antimicrobial agents in various medical disciplines. For example, toothpaste containing zinc nanoparticles can be produced and prescribed for patients with immune deficiency to prevent the growth of microbial pathogens in the mouth and its transmission to the patient's body.