Antimicrobial Evaluation of Biologically Synthesized Silver Nanoparticles using Aqueous Peel Extracts of Guava (Psidium guavaja) and Pumpkin (cucurbita pepo)

Introduction: Green nanoparticle synthesis is a new field of nanotechnology that uses ecologically friendly resources such as entire cells, metabolites, agricultural waste such as peel, or extracts from plants and microbes to make metallic nanoparticles. In this study, silver nanoparticles were synthesized from aqueous extracts of Psidium guavaja (Guava) and Cucurbita pepo (Pumpkin) peels, and their antibacterial properties were evaluated against gram positive and negative bacterial isolates.

Methods: The effect of silver nanoparticles was tested against Staphylococcus aureus, Proteus mirabilis, and Gentamycin antibiotic sensitivity disks used as positive control, and the synthesised nanoparticles were analyzed using UV-visible spectroscopy, SEM, and FTIR.

Results: The UV-visible spectra obtained at different peaks between 200nm and 700nm confirmed the presence of synthesized silver nanoparticles, while the FTIR revealed the presence of certain functional groups such as C=C stretch, C-H bonding, and Alcohol OH stretch, which represent bioactive compounds such as phenol, amine, and others. The capping and reducing properties of the produced silver nanoparticles are due to these biomolecules. The SEM indicated that synthesized nanoparticles had a spherical, hexagonal, rod, and triangular form. The antibacterial activities of the Nano-particles, such as MIC and MBC, demonstrated their efficiency against the tested bacterial isolate. Antibacterial activity of guava and pumpkin nanoparticles against Proteus mirabilis and Staphylococcus aureus were found to be effective.

Conclusion: The studies confirmed that aqueous peel extract of Psidium guavaja (Guava) and Cucurbita pepo (Pumpkin) are good sources for synthesis of silver nano-particles via green route, the biologically synthesized silver nano-particles were found to have effective broad spectrum of antimicrobial activity against Staphylococcus aureus and Proteus mirabilis.