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

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.