Precursor Dependent Tailoring of Morphology and Crystallite Size of Biogenic ZnO Nanostructures with Enhanced Antimicrobial Activity- a Novel Green Chemistry Approach

During recent years, there has been a growing pursuit in researching and developing new therapeutic antimicrobial agents from several sources to combat microbial resistance. Therefore, a greater attention has been paid in screening of antimicrobial activity and evaluating methods. The objective of the present study was to synthesize, characterize, and explore nanosized biogenic zinc oxide (ZnO) NPs and evaluate its performance for the antimicrobial activity. Biogenic zinc oxide nanoparticles (ZnO NPs) were fabricated with the two different zinc salts (zinc acetate and zinc nitrate) from aqueous Achyranthes aspera leaf extract and characterized using modern methods and tools, such as X-ray diffraction, Fourier transform infrared spectroscopy, and UV-vis spectroscopy, which indicated the formation of very pure ZnO NPs. The scanning electron microscopic analysis (SEM) explored the formation of flower-like morphology in the sample of zinc acetate precursor and spherical morphology in the sample of zinc nitrate precursor. Further, the elemental composition of both samples was analyzed by energy dispersive spectroscopy (EDS). The antibacterial of ZnO NPs was evaluated by disk diffusion method on Gram-negative pathogen Escherichia coli and Gram-positive pathogen Staphylococcus aureus. ZnO nanoparticles exhibited a higher zone of inhibition (29 mm) because of having a larger specific surface area. Minimum inhibitory concentration (MIC) values of biogenic ZnO NPs were observed in the range of 40–60 μg/mL against selected oral pathogens. Overall, the green synthesized ZnO NPs demonstrated the astounding potential for the antimicrobial activity as an alternative clean-green therapeutic solution.