In vitro and In vivo toxicity assessment of phytofabricated ZnO nanoparticles showing bacteriostatic effect and larvicidal efficacy against Culex quinquefasciatus.

Murraya koenigii berry extract based zinc oxide nanoparticles (Mk-ZnO NPs) were synthesized by simple co-precipitation method and examined for bacteriostatic and larvicidal efficiency. Synthesized Mk-ZnO NPs were characterized by UV-Vis spectroscopy at 336 nm. X-Ray diffraction (XRD) showed crystalline nature as hexagonal. Fourier transform infrared spectroscopy (FTIR) spectrum exhibited strong peak at 3442.80 cm-1. Field emission scanning electron microscopy (FE-SEM) showed hexagonal shape of the particle. Transmission electron microscopy (TEM) measured 10-15 nm sized Mk-ZnO NPs. EDX peaks confirm 71.99% of zinc and 11.42% of oxide in Mk-ZnO NPs. Minimum inhibitory concentration (MIC) analysis reveals Mk-ZnO NPs inhibit growth of Gram positive (Staphylococcus aureus, Lysinibacillus fusiformis) and Gram negative (Proteus vulgaris, Providencia vermicola) bacteria at 40 and 50 μg mL-1 respectively. Live & dead assay confirms that Mk-ZnO NPs inhibits bacterial growth at 50 μg mL-1. Bacterial biofilm thickness significantly reduced by Mk-ZnO NPs at 50 μg mL-1. In vitro toxicity of Mk-ZnO NPs on RAW 264.7 macrophages determines 90-50% cell viability at concentrations of 10-100 μg mL-1. In vivo toxicity assay results indicate the lethal concentration of Artemia nauplii were LC50-78.73 μg mL-1 and LC90-130.03 μg mL-1. Larvicidal activity of Mk-ZnO NPs towards mosquito larvae of Culex quinquefasciatus were observed at LC50-2.1 μg mL-1 and LC90-12.1 μg mL-1. Finally the study discloses, potential bacteriostatic effect and mosquito larvae controlling capacity of Mk-ZnO NPs.