Characterization and investigation of antioxidant and antimicrobial activity of zinc oxide nanoparticles prepared using leaves extract of Nyctanthes arbor-tristis

Abstract

Due to the emergence of multidrug resistance, the occurrence of microbial infections has increased by several times during the last decade. In addition, a significant challenge in green nanotechnology is to develop an environment-friendly and simple route to produce different metal oxide nanoparticles. Hence, the goal of the present study is to synthesize and evaluate the antimicrobial efficacy of Nyctanthes arbor-tristis (NA) leaves extract decorated zinc oxide nanoparticles (ZnO-NA). The structural, morphological, and optical assessments of the ZnO-NA nanoparticles were carried out via Field emission scanning electron microscopy (FE-SEM), Powder X-ray diffraction (PXRD), UV–Visible spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). The interaction of as synthesized ZnO-NA with bacteria was confirmed by energy dispersive spectroscopic (EDS) analysis. The PXRD pattern revealed the hexagonal wurtzite crystalline structure whereas from UV–Visible spectroscopy, obtained absorbance peak at 370 nm confirmed the formation of ZnO-NA. The interactions of the phytoconstituents present in the aqueous extract of Nyctanthes arbor-tristis with zinc oxide nanoparticles were established from the spectra of FT-IR analysis. Furthermore, the FE-SEM micrographs revealed thenanotilesshape of the synthesized ZnO-NA with the rough surface having nanocracks. The thickness and length of these nanotiles were calculated at approximately 75–150 nm and 550–600 nm respectively.The intercept and slope values obtained from this plot were 0.00675 and 0.01013 respectively. The crystallite size obtained from the Williamson-Hall (W-H) plot was 21.45 nm. The DPPH (2, 2-diphenyl-1-picryl-hydrazyl-hydrate) assay was employed for studying the antioxidant activity of the leaves extract of the Nyctanthes arbor-tristis plant. The IC50 value was observed to be 125 µg/mL. Besides, the antimicrobial efficacy of the green synthesized ZnO-NA nanoparticles was reported against two bacterial strains, Staphylococcus aureus (gram-positive) and Acinetobacter baumannii (gram-negative) bacteria using an agar well diffusion test and a micro broth dilution assay. Maximum zone of inhibition was obtained 7 ± 0.1 mm against Staphylococcus aureus and 0.5 ± 0.05 mm and 0.5 ± 0.10 mm against Acinetobacter baumannii respectively. The minimum inhibitory concentration (MIC) values were observed at 12.5 mg/mL for Staphylococcus aureus and 3.125 mg/mL for Acinetobacter baumannii, respectively. Therefore, the results of MIC values suggested that green synthesized ZnO-NA nanoparticles could be used as an alternative drug in the medical field to treat bacterial infections..