Citrus limon based synthesis of zinc oxide nanoparticles: Antibacterial applications with improved outcomes

Abstract

Background: Biosynthesis of nanoparticles by biological means, especially plant extract plays a major role in the field of nanotechnology. Zinc Oxide nanoparticles (ZnO-NPs) along with natural resources have demonstrated several advantages over traditional synthetic processes, including ease of use, low cost, eco-friendliness, nontoxic by products, and the absence of critical temperature and pressure conditions.

Methods: In the present study, the aqueous extract of lemon (Citrus limon) peel, pulp and leaves was used for the green synthesis of ZnO-NPs using 0.1 M Zinc nitrate dihydrate (Zn (NO3) 2) as a precursor in alkaline condition using NaOH. UV-visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) analysis and Scanning Electron Microscopy (SEM) were used to characterize the structures. Disc diffusion method was used to evaluate the antibacterial effects of the synthesized nanoparticles.

Results: ZnO-NPs obtained were characterized by UV-visible spectroscopy in which the surface plasmon resonance was 280 nm. FTIR analysis showed appropriate peaks for various chemical groups present in ZnO-NPs and stretching vibrations at 432 cm-1 indicating the presence of Zinc oxide bond in nanoparticles. SEM results showed spherical and well dispersed structures. Antibacterial property of ZnO-NPs, evaluated by the well diffusion assay, showed zone of inhibition in various pathogenic strains of Gram positive as well as Gram negative bacteria. It was observed that pulp-based nanoparticles had highest activity amongst all strains.

Conclusion: Use of aqueous lemon extract as a capping agent would improve the antibacterial property of ZnO-NPs and can be developed as antibacterial agents against a wide range of microorganisms to control and prevent bacterial infections.