Antibacterial and antioxidant activities of Ag-Mn bimetallic nanoparticles mediated by mango (Mangifera indica l.) Leaf extract

This study investigated the synthesis, characterization, antibacterial and antioxidant activities of silver–manganese (Ag–Mn) bimetallic nanoparticles using Mangifera indica leaf extract. Ag–Mn nanoparticles were synthesized through a one-pot green synthesis approach and characterized using UV–Vis spectroscopy, FTIR, SEM, and EDX analyses. The antibacterial activities were accessed using the agar well diffusion method and antioxidant activities by DPPH and ABTS assays.  The UV–Vis spectra exhibited a distinct surface plasmon resonance peak at 445 nm, confirming the presence of Ag nanoparticles, along with minor peaks attributable to Mn interactions. FTIR analysis revealed functional groups such as hydroxyl, carboxylic, and carbonyl bands that acted as reducing and stabilizing agents. SEM images displayed irregular, non-spherical nanoparticles with moderate aggregation, while EDX confirmed the elemental composition of Ag and Mn. The antibacterial evaluation demonstrated that the Ag–Mn nanoparticles exhibited broad-spectrum activity, with the highest inhibition against Klebsiella pneumonia (19.98 ± 1.03mm), followed by Pseudomonas aeruginosa, Salmonella typhi, and E. coli. Antioxidant assays showed that the Ag–Mn NPs showed dose-dependent radical scavenging activity. The ABTS assay outperformed ascorbic acid at concentrations ≤40 μg/mL, with an IC₅₀ of 31.25 μg/mL. The DPPH IC₅₀ was 23.74 μg/mL, slightly lower than that of ascorbic acid. The synthesized Ag–Mn bimetallic nanoparticles showed strong antibacterial and antioxidant potential, due to the combined impacts of silver and manganese, and the capping influence of phytochemicals in M. indica leaf extract. These findings suggest their application in biomedical and pharmaceutical as eco-friendly therapeutic agents.