Sonchus Asper Mediated Green Synthesis of ZnO Nanoparticles, their Characterization and Antimicrobial Activities

Abstract

Herein, we report on green synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Sonchus asper as a natural reducing and stabilizing agent. Unlike physical and chemical synthesis routes, the biosynthesis approach presents a low-cost and eco-friendly strategy. A well-defined morphological and crystalline structure of nanoparticles (NPs) were confirmed in nano-form by analytical techniques viz. UV-Vis spectroscopy absorption (365-370 nm). Fourier transform infrared spectroscopy (FTIR) gave absorption at 3350, 569 and 448 cm^-1. X-ray diffraction (XRD) gave crystalline pattern and 26 nm size of ZnO NPs, electron microscopy, etc of the particles obtained after reaction. Sonchus asper leaf extract provides phytochemicals that help reduce zinc ions and cap particles, thereby producing stable ZnO NPs. The synthesized ZnO NPs exhibited several functional properties, particularly their antibacterial activity against a variety of harmful bacteria, displaying potential applicability in biological and environmental applications. SEM showed agglomeration and porous surface morphology. These results indicate that the green method of synthesizing ZnO nanoparticles with Sonchus asper leaves is a sustainable and effective way to produce these nanomaterials with bioapplications. Moreover, the synthesized ZnO NPs showed considerable antibacterial activity against Gram-positive as well as Gram-negative bacterial strains thus indicating its broad-spectrum antimicrobial potential. Average inhibition zones of regarding antibacterial activity of four bacteria were: Bacillus subtilis (17.5 mm), Staphylococcus aureus (16.75 mm), Klebsiella pneumoniae (21.5 mm) and Escherichia coli (18.5 mm).

Keywords: Sonchus asper, zinc oxide, nanoparticles, green synthesis