Comparison of the Physical Characteristics of Green-Synthesized and Commercial Silver Nanoparticles: Evaluation of Antimicrobial and Cytotoxic Effects

We investigated a novel green route synthesis of silver nanoparticles (AgNPs) using watermelon rind powder extract (WR-AgNPs) as a reducing and capping agent. The efficiency of nanoparticle synthesis was evaluated by comparing the structure, functional groups, antibacterial activity, and cytotoxic effects with commercial AgNPs (C-AgNPs). The AgNP production was initially confirmed based on color changes and wavelength scanning by ultraviolet–visible spectra, which exhibited a surface plasmon resonance peak at 450 nm. We used energy-dispersive spectroscopy to confirm silver and sample purity of both experimental and commercial AgNPs from 2 to 4 keV. Fourier transform infrared spectroscopy analysis showed that the AgNPs were reduced and capped with biomolecules from functional groups in the watermelon powder extract. Further, the analysis showed that the synthesized AgNPs were similar to C-AgNPs. The morphology and crystalline nature of both AgNPs were determined using high-resolution transmission electron microscopy and X-ray powder diffraction. In addition, the synthesized and commercial AgNPs were subjected to antibacterial and cytotoxicity assays. Three-way ANOVA indicated that treatments for WR-AgNPs or C-AgNPs as well as concentration and time had significant effects on Brevibacterium linens and Staphylococcus epidermidis—an odor-causing bacteria. With respect to cytotoxic effects, 67 % cell death was observed with high concentrations (10 mg/L) of both AgNPs.