Eco-friendly biosynthesis of manganese oxide-silver bimetallic nanoparticles using Cucumis melo peel extract: characterization, antioxidant, antimicrobial, and antiviral activities

The employment of plant extracts for green production of bimetallic nanoparticles (BNPs) has gotten significant consideration because of its cheap, ecological, single-step, and easily scalable procedures. This methodology enables the manufacture of biocompatible nanoparticles (NPs) with improved activity. In this study, an environmentally friendly approach was utilized to biosynthesize manganese oxide-silver BNPs (MnO-Ag BNPs) using Cucumis melo (C. melo) peel extract (CPE), which served as the source of the required reducing and stabilizing materials. Several spectroscopic analytical methods, including ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were applied for careful confirmation and characterization of successful MnO-Ag BNPs assembly. This work introduces a novel green route employing CPE for MnO-Ag BNPs synthesis, providing distinct phytochemical efficiency and multifunctional bioactivity compared with previously reported plant-based systems. The biosynthesized MnO-Ag BNPs bacterial inhibitory capability as well as free radical scavenging effect were evaluated. Also, human kidney normal epithelial-derived cells (Vero cell line CCL-81) was employed for assessment of the cytotoxic outcome of MnO-Ag BNPs at various concentrations. Regarding the elemental composition, the manganese (Mn) and Ag contents were detected by the UV-vis, XRD, and EDX studies with consequent validation of MnO-Ag BNPs biosynthesis. The range of the assessed BNPs size was 2 to 10 nm with average diameter of 5.8 ± 1.7 nm and an average area of 22.7 nm². Analysis based on EDX technique revealed the presence of Mn and Ag metals with 23.7-46.6% of the atomic percentages and 32.2-28.0% of the weight percentages, respectively. The biosynthesized NPs showed strong free radical scavenging, achieving 85-90% inhibition at higher concentrations. The cytotoxic activity findings indicated no significant harmful effects, at concentration range of 31.25-250 µg/mL, on Vero cell line. Additionally, the viability of the tested cell line infected with herpes simplex virus type-1 (HSV-1) significantly increased from 43% (untreated) to 78-99% when treated with 125 µg/mL MnO-Ag BNPs and acyclovir, respectively. Moreover, the inhibition rates achieved against the tested virus were 73% for MnO-Ag BNPs and 99% for acyclovir. These outcomes highlight the potential of MnO-Ag BNPs as promising candidates for biomedical and antiviral applications.