Antibacterial and Antioxidant Activities of ZnO Nanoparticles Synthesized Using Extracts of Allium sativum,Rosmarinus officinalis and Ocimum basilicum

ZnO nanoparticles (ZnO NPs) were synthesized by chemical method (coprecipitation) and biological method using aqueous extracts of garlic (Allium sativum), rosemary (Rosmarinus officinalis) and basil (Ocimum basilicum). The influence of plant extract on the antibacterial and antioxidant activities of green synthesized nanoparticles was investigated. The X-ray diffraction studies reveal that all ZnO samples have hexagonal wurtzite structure. The particle size of ZnO NPs estimated by transmission electron microscopy analysis (between 14 and 27 nm) varies depending on the synthesis method of nanoparticles and the type of extracts from the plants used. The functional groups involved in the biosynthetic procedure were evidenced by Fourier transform infrared spectroscopy. The presence of Mn2+ ions, Zn vacancy complexes and oxygen vacancies in ZnO samples was highlighted by electron paramagnetic resonance spectroscopy. The green synthesized ZnO NPs have shown a good bactericidal activity against Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa bacterial strains. ZnO NPs synthesized using extracts of the selected plant species have been found to exhibit more enhanced antibacterial and antioxidant activities as compared to chemical ZnO NPs.