Extracellular synthesis of silver nanoparticles by bioluminescent bacteria: characterization and evaluation of its antibacterial and antioxidant properties

In this study, the silver nanoparticles (AgNPs) were extracellularly synthesized using a bioluminescent bacterium, Vibrio campbellii, and characterized their functional properties and morphological nature by UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDS), and atomic force microscopy (AFM). Further, the synthesized AgNPs were analyzed for their antibacterial and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), and hydrogen peroxide) in in vitro method. The antibacterial activity of AgNPs was tested against pathogenic bacteria such as Aeromonas hydrophila MTCC 1739, Klebsiella pneumoniae MTCC 4030, Klebsiella oxytoca MTCC 3030, and Pseudomonas aeruginosa MTCC 1934. Characterization studies revealed that the synthesized AgNPs were poly-dispersed, spherical shaped with various size ranges, and exhibited as crystalline in nature. The assay of antibacterial activity showed the synthesized AgNPs strongly inhibited the tested pathogenic bacterial growth. Also, the AgNPs showed good antioxidant activity by strong scavenging actions on DPPH (61.88%) and hydrogen peroxide (53.48%) free radicals. Overall results demonstrated that AgNPs could be used in the pharmaceutical field due to their good antibacterial and antioxidant activity.