Antimicrobial Activity of Zinc Oxide Nanoparticles Synthesized by using Leaf Extract of Amaltas (Cassia fistula)

Muhammad Arshad1, Sajida Naseem1, Javeria Gulzar1, Muhammad Shahzad1, Muhammad Zain Hassan1

1University of Education, Township Campus, Lahore


The improper and frequent use of standard drugs against bacterial and fungal pathogens is causing the emergence of resistance in them. So, there is a need to investigate the powerful antimicrobial agent which presents good antimicrobial property. Nowadays, nano-sized particles are proved to be the most effective antimicrobial agents by researchers.

Due to the unique characteristics, Zinc oxide nanoparticles (ZnO NPs) has achieved more attention. Nanoparticles that are prepared by using conventional methods have limited applications due to toxicity mechanisms. So, using the extracts of medicinal plants to biosynthesize nanoparticles is an eco-friendly approach and cost effective process. The aim of present study was to investigate the antimicrobial potential against bacterial and fungal isolates. ZnO NPs were biosynthesized by adding the varying concentrations of Cassia fistula leaf extract (10 ml, 20 ml and 30 ml) in 50 ml zinc nitrate hexahydrate solution. Formation of dirty coloured precipitates initially indicated the presence of ZnO NPs.

Their size and surface morphology was analyzed by using Scanning Electron Microscope (SEM). Three samples of NPs (A, B, C) were found to have an average size of 85 nm, 70 nm and 80 nm, respectively. SEM analysis also exhibited the shapes of NPs to be flake type structures and nanorods. Energy Dispersive X-ray (EDX) analysis further confirmed that these nanoparticles had pure ZnO. The antimicrobial efficiency was assessed against two bacterial strains i.e. Staphylococcus aureus and Basillus subtilus; as well as one fungal strain i.e., Candida albicans through well diffusion assay based on the zone of inhibition. Excellent antimicrobial activity was shown by ZnO NPs as compared to the standard drugs. It was concluded that plant based synthesis of ZnO NPs were proved to have the potential to inhibit the growth of tested microbes.   Keywords: Cassia fistula, green synthesis, zinc oxide, energy dispersive x-ray, antimicrobial activity.

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