Biocompatibility assessment and photocatalytic activity of bio-hydrothermal synthesis of ZnO nanoparticles by Thymus vulgaris leaf extract

Abstract

A facile synthetic route and growth mechanism of phytochemicals stabilized zinc oxide (ZnO) nanoparticles have been developed using Thymus vulgaris (Thyme) leaf extract via hydrothermal method. Using thyme leaf extract as a size reducing agent with zinc nitrate as precursor via hydrothermal method is the novelty of this work. Presence of flavonoids, phenols and saponins in Thyme leaf extract has served as both reducing and stabilizing agents that play a critical role in the production of ZnO nanoparticles. The obtained ZnO nanoparticles having 50−60 nm size with an irregular shape. The in-vitro antioxidant activity by DPPH assay showed prominent activity (<75%) for higher concentration (10 mg/ml) of tested ZnO nanoparticles. The antimicrobial activity of ZnO nanoparticles against selected foodborne pathogens revealed that the tested gram-negative bacteria are more pronounced than the tested gram-positive bacteria. The maximum hemolysis percentage for all the samples were less than ∼3% (up to 6 mg/ml) which is much lesser than permissible limit. The results showed the great photocatalytic degradation of methylene blue (MB) as compared to Control (TiO2-P25). Results of this study reveals that Thyme leaf extract containing phytochemicals possess reducing property for ZnO nanosize fabrication and the obtained ZnO nanoparticles could be employed effectively for biological applications and food science.