Biogenic synthesis of silver-functionalized iron and copper oxide nanocomposites using the aqueous extract of Psidium guajava fruit

Here, we present a green coprecipitation synthesis route for silver-functionalized copper and iron oxide nanocomposites (Cu2O/CuO/Fe2O3@Ag) using guava (Psidium guajava) fruit extract as reducing and stabilizing agent. The novelty of this approach lies in the unexplored use of guava, a widely available biomass rich in phytochemicals, to produce multifunctional nanocomposites with enhanced properties. The structural and morphological analyses (XRD, FTIR, SEM, TEM) confirmed the presence of crystalline phases of Fe2O3, Cu2O, CuO, and Ag, along with nanoflake-like and sphericlike morphologies and nanometric particle sizes. Magnetic characterization (VSM) revealed a change from paramagnetic behavior in non-functionalized samples to weak ferromagnetism with reduced coercivity and magnetization upon silver incorporation. The antibacterial assays demonstrated that the functionalized nanocomposites exhibited strong inhibitory effects against the multidrug-resistant pathogen Klebsiella pneumoniae, achieving substantial growth inhibition at 500 ppm. Our findings highlight the potential of guava fruit extract as a sustainable precursor for the biogenic synthesis of silver-functionalized Fe–Cu oxide nanocomposites, offering a promising route for environmentally friendly nanomaterials with applications in biomedical and environmental fields.