Bio-Fabrication of Euryale ferox (Makhana) Leaf Silver Nanoparticles and Their Antibacterial, Antioxidant and Cytotoxic Potential

Bio-fabrication of green or plant extract-based silver nanoparticles has garnered much praise over the past decade as the methodology is environment-friendly, undemanding, non-pathogenic, and economical. In the current study, leaves of Eurale ferox (Makhana), considered as waste, were used for the bio-fabrication of silver nanoparticles (ELAgNPs). Various analytical techniques including UV-VIS spectroscopy, Field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (FESEM-EDX), Particle size analyzer (PSA), Fourier transform infra-red spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM) were used for their characterization. Their antibacterial efficacy was examined against gram positive bacterium, Bacillus subtilis and gram negative bacterium, Escherichia coli. The antioxidant potential of the ELAgNPs was compassed by 2, 2 diphenyl-1-picryl hydrazyl (DPPH; lambda(max) = 517 nm) assay, H2O2 (lambda(max) = 230 nm) and OH- (lambda(max) = 520 nm)-based radical scavenging assays. The cytotoxicity was checked against the VERO cell line using 3-[4, 5-dimethyl thiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay. A mean particle size of 26.51 +/- 8.87 nm with a size distribution of 7.08-53.94 nm was obtained using HRTEM. The ELAgNPs exhibited dose-dependent antibacterial efficacy with a maximum zone of inhibition (ZOI) of 21.98 +/- 0.59 mm against B. subtilis and of 16.46 +/- 0.22 mm against E. coli at 500 ppm after 24 h of incubation. The median lethal concentration for the cytotoxicity analysis was found to be 9.54 +/- 0.35 ppm, 120.9 +/- 6.31 ppm, and 20.74 +/- 0.63 ppm for ELAgNPs, commercial silver nanoparticles (CAgNPs), and silver nitrate (SN), respectively. The ordinary one-way ANOVA results exhibited a significant decrease in cell viability after 72 h of incubation at p < 0.05, alpha = 0.05. In conclusion, the ELAgNPs showed good antibacterial, radical scavenging and dose-dependent cytotoxicity against the VERO cells. Therefore, these could be used for biomedical applications. Phyto-constituents present in the plant not only act as reducing agents but also as stabilizing and coating agents, and the availability of a wide range of metabolites makes the green approach more promising.