Mahmood Alizadeh-Sani
1,2 
, Hamed Hamishehkar
3 , Arezou Khezerlou
2 , Mohammad Maleki
4, Maryam Azizi-Lalabadi
2, Vahid Bagheri
5 , Payam Safaei
1, Taher Azimi
6,7 , Mohammad Hashemi
8, Ali Ehsani
9* 1 Student’s Scientific Research Center, Food Safety and Hygiene Division, Environmental Health Department, School of Public Health, Tehran University Of Medical Sciences, Tehran, Iran.
2 Students Research Committee, Department of Food Sciences and Technology, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
3 Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
4 Department of Food Hygiene and Aquaculture, Ferdowsi university of Mashhad, Mashhad, Iran.
5 Department of Food Science and Technology, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
6 Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
7 Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
8 Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
9 Nutrition Research Center, Department of Food Sciences and Technology, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
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.