Study the effect of simple extraction techniques to synthesizing promising antimicrobial bio-capped copper oxide nanoparticles

Six samples of bio-capped copper oxide nanoparticles were made from two bio-waste extracts: Punica granatum L. peels and Psidium guajava Linn. leaves. Extraction methods included soaking in water or hydroethanol and boiling in water. The samples were characterized using FT-IR, XRD, SEM, and TGA. Results showed organic residue capping on CuO nanoparticles varied based on the extract and capping medium used. The thermal stability of all CuO samples was observed to be high, as recorded from TGA patterns and confirmed by EDX analysis, which showed a high content of copper ranging from 10.1 to 36.1%. TEM analysis revealed an average particle size of less than 20 nm for all six samples, suggesting a similarity in size. The soaking technique produced the most stable bio-capped CuO nanoparticles with a high negative zeta potential value. According to the study, the CuO samples synthesized from aqueous extracts obtained through soaking showed the highest antibacterial activity. This could be attributed to the high oxygen ratio, which was confirmed via EDX analysis. The bio-capped CuO was effective against multidrug- resistant gram-positive bacteria MRSA, and C. albicans. A mechanism was proposed to explain how the capping media affected the antimicrobial activity of the bio-capped CuO nanoparticles.