ABSTRACT
Zinc oxide nanoparticles (ZnO NPs) are one of the most abundant metal oxides nanoparticles. It provides excellent thermal, electrical and chemical stabilities with low biotoxicity; its photo-oxidising and photo-catalytic impact on biological and chemical species is of great importance, thereby making it a promising candidate to be used for in-vitro and in-vivo studies in biomedical field. Hereby, ZnO NPs were synthesized using precipitation method with zinc acetate and sodium hydroxide as starting materials. This study has characterized the synthesized ZnO NPs using different techniques such as UV-Visible spectroscopy indicating a peak at 365 nm wave length, size of ZnO NPs was determined to be 286.7 nm by measuring hydrodynamic radii using Dynamic Light Scattering (DLS) phenomena. Further predominant charge existing at surface of the synthesised ZnO NPs was evaluated to be 31.6mV. Anti-microbial activity of ZnO NPs was determined by Kirby-Bauer method for both Gram-positive and Gram-negative bacteria, S. aureus and E. colirespectively. Anti-microbial activity was determined as Zone of Inhibition that measures both bactericidal and bacteriostatic activity of ZnO NPs and was found to be more potent for Gram-positive (S. aureus)bacteria and its activity increased with increasing concentration of nanoparticles. Growth kinetics was studied to determine percentage growth inhibition, for this optical density was recorded as a function of time in bacterial culture broth with and without treatment. Further DNA fragmentation assay was performed to determine genotoxicity caused by nanoparticles and its effect on genomic DNA of bacteria. Highlighting its potential role as a nano-carrier system for leading antibacterial drugs for enhanced effectiveness of the antibacterial therapies
ABSTRACT
Background: Zinc oxide nanoparticles (ZnO-NPs) are frequently used in many fields, including food industry fortheir antimicrobial activity. Acute exposure to high doses of such particles was found to be toxic to many organs.However, the lung toxicity resulting from chronic exposure to oral doses of ZnO-NPs was not adequately assessedbefore.Aim of the work: to detect the anatomical and histopathological effects of chronic exposure to ingested ZnO-NPson the lung of normal adult male albino rat.Material and methods: It was carried out on 30 adult male Swiss albino rats with an average weight of 150-200gm. They were divided into two groups: Group I: 10 rats serving as control group; Group II: 20 rats serving asexperimental groups, divided into 2 subgroups (a&b) receiving oral ingestion by orogastric tube of a single dailydose (125mg/ kg) of average 20 nm sized ZnO-NPs for different durations: Group IIa (n=10): for 120 days; GroupIIb (n=10): for 180 days. Histopathology and immunohistochemistry of the lungs in the three groups was performedto detect the possible effect of such exposure.Results: Oral administration of ZnO-NPs induced lung damage manifested by congested blood vessels, interstitialinflammation, infiltration with macrophages& lymphocytes, supurative granuloma, thickened interalveolarsepta. These changes were more evident with longer exposure for 180 days (P < 0.5). This substantial damage tothe lungs is caused by oxidative stress and chronic inflammation.Conclusion: Caution should be considered when using these particles in food packaging and food additives, andfor those who are in close contact with these particles especially in factories.