Evaluation of antibacterial and cytotoxic effects of silver oxide nanoparticles synthesized from Psidium Guajava

Growing concerns over the toxicity and environmental impact of traditional nanoparticle synthesis methods have driven the search for safer, more sustainable alternatives. At the same time, the rising prevalence of antibiotic-resistant bacteria and the ongoing challenges in effective cancer treatment emphasize the urgent need for new antimicrobial and anticancer solutions. The manufacture of silver oxide nanoparticles (Ag₂O-NPs) is investigated in this work using Psidium guajava (guava) leaves extract, focusing on their dual biological potential. The use of dangerous chemicals is reduced by this green synthesis technique by employing natural phytochemicals from guava leaves as stabilizing and reducing agents, making it more environmentally friendly compared to traditional chemical approaches. At 435 nm, the biosynthesized Ag₂O-NPs displayed a distinctive surface plasmon resonance (SPR) band. With a polydispersity index (PDI) of 0.368. Nanocrystalline, mostly spherical Ag₂O-NPs with an average size of 25 to 30 nm were successfully formed, according to thorough characterization utilizing FTIR, XRD, SEM, TEM, and EDX. These nanoparticles demonstrated strong antibacterial activity against four clinically relevant, drug-resistant bacterial strains: Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium ATCC 13311, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 29213. Minimum inhibitory concentration (MIC) values ranged from 31.2 to 250 µg/mL, indicating a dose-dependent antibacterial action. Notably, P. aeruginosa and S. aureus showed the highest sensitivity. Cytotoxicity testing further revealed selective anticancer activity, with the Ag₂O-NPs significantly reducing the viability of HepG2 liver cancer cells (IC₅₀ = 73.93 ± 0.49 µg/mL), while displaying lower toxicity toward normal Vero cells (IC₅₀ = 158.1 ± 0.41 µg/mL). These findings suggest that green-synthesized Ag₂O-NPs hold considerable promise as both potent antibacterial agents and effective anticancer therapeutics.