Antimicrobial Activity of Green Synthesized Copper Nanoparticles (CuNPs) using Aqueous Extract of Psidium Guajava on Clinical Bacteria Isolates.

13 December 2023, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The green synthesis of nanoparticles utilizing an aqueous plant extract as a capping and stabilizing agent has attracted significant attention across diverse fields, particularly in pharmaceuticals and drug delivery. In this investigation, Copper Sulfate Pentahydrate (CuSO4.5H2O) salt served as a precursor for synthesizing copper nanoparticles at pH 4-5 and pH 8, employing Psidium guajava (leaves and fruits) extract for characterization. Fourier Transform Infrared (FTIR) spectroscopy revealed four major functional groups at distinct peaks (3235.3 cm-1, 2109.7 cm-1, 1640.0 cm-1, and 1069.7 cm-1) responsible for capping and stabilizing the synthesized P.g-CuNPs. Scanning Electron Microscopy (SEM) displayed spherical shapes for the synthesized P.g-CuNPs, with an average particle size range of 20-30 nm. Energy-dispersive X-ray (EDX) analysis of the synthesized P.g-CuNPs indicated the presence of pure copper (Cu) at 54.15%, occurring at regions of 1, 8, and 9 keV. P.g-CuNPs synthesized at pH 4-5 exhibited complete growth inhibition of all tested bacterial strains at concentrations of 0.1, 0.25, and 0.5 mg/mL. Serially diluted P.g-CuNPs (pH 5) demonstrated inhibition of Salmonella spp, E.coli, and Streptococcus spp at 100 µg/mL, while serially diluted P.g-CuNPs (pH 8) only showed inhibition of E.coli at 100 µg/mL. The acid-based synthesized P.g-CuNPs exhibited a higher degree of efficacy in the antimicrobial study compared to the alkaline-based synthesized P.g-CuNPs. Based on the study's findings, P.g-CuNPs derived from Psidium guajava can be employed for various biomedical purposes, such as incorporating them as a therapeutic drug for enhanced efficacy against microbial infectious diseases, integrating them into textile coatings for fiber, and employing nanocapsulation for food storage to extend the shelf life of food items.


Copper nanoparticles
Psidium guajava
drug-resistant bacteria
green synthesis
Salmonella spp
E. coli
S. aureus
streptococcus spp.


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