Abstract
Purpose: The increase of bacterial resistance to common antibacterial agents is one of the major problems of health care systems and hospital infection control programs. In this study, antimicrobial activity of titanium dioxide (TiO2 ) and zinc oxide (ZnO) nanoparticles (NPs) was investigated against E. coli, Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus pathogenic bacteria by determining sensitivity coefficient and kinetics of bacterial death. Methods: Antimicrobial tests were performed with ~106 CFU/mL of each bacterium at baseline. At first, minimum inhibitory concentration (MIC) was concluded by the dilution method and then, death kinetic and susceptibility coefficient of NPs suspensions was determined at 0 to 360 min. treatment time. Results: The results of this study revealed that, the highest susceptibility was observed for L. monocytogenes (Z=0.025 mL/μg) to TiO2 NPs, whereas the lowest susceptibility was obtained in the reaction of ZnO NPs with S. enteritidis (Z=0.0033 mL/μg). The process of bacterial death in NPs suspension was assumed to follow first-degree kinetic and the survival ratio of bacteria decreased by the increase in treatment time. An increase in the concentration of NPs was seen to enhance the bactericidal action. Conclusion: Results showed that L. monocytogenes had higher sensitivity compared to S. enteritidis. The results of this study also demonstrated that TiO2 NPs have a strong antimicrobial effect in comparison with ZnO NPs and it could be employed to aid the control of pathogenic bacteria.
Highlights
IntroductionNanotechnology has been increasingly applied in different fields, especially in medical, food and Pathogenic bacteria and TiO2/zinc oxide (ZnO) nanoparticles: Kinetic analysis pharmaceutical domains.[12,13,14] Among various NPs, TiO2 and ZnO are widely used due to their strong antimicrobial effects
Nowadays, new approaches are required to control harmful microorganisms
The results of this study revealed that, the highest susceptibility was observed for L. monocytogenes (Z=0.025 mL/μg) to TiO2 NPs, whereas the lowest susceptibility was obtained in the reaction of zinc oxide (ZnO) NPs with S. enteritidis (Z = 0.0033 mL/μg)
Summary
Nanotechnology has been increasingly applied in different fields, especially in medical, food and Pathogenic bacteria and TiO2/ZnO nanoparticles: Kinetic analysis pharmaceutical domains.[12,13,14] Among various NPs, TiO2 and ZnO are widely used due to their strong antimicrobial effects. These materials, when synthesized on a nanoscale, exhibit strong antimicrobial effects because of an increase in surface-to-volume ratio and their specific surface area.[15,16] It has been suggested that these nanomaterials react with proteins especially with -SH groups; which leads to protein inactivation.[11,15] Several studies have reported the antimicrobial effects of various NPs such as silver and copper against E. coli and Bacillus subtilis,[17] silver NPs against multidrug-resistant bacteria[18] and TiO2 NPs against pathogenic bacteria.[8,19] According to the results obtained by various tests such as proteomics research, transmission electron microscopy (TEM) and scanning electron microscopy, it is proposed that the mechanism of antimicrobial activity varies from one nanoparticle to another, because NPs react with important elements of bacterial membrane and cell wall, which cause structural change and damage, destruction of the proton motive force, and cell death.[11,20,21] Nanoantimicrobial agents can be used in coating surfaces in order to produce antimicrobial characteristics in food and in medical devices and water treatment filters.[22]
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