Photocatalytic degradation of caffeine and E. coli inactivation using silver oxide nanoparticles obtained by a facile green co-reduction method

In this study, silver oxide nanoparticles (Ag2O-NPs) were synthesized from silver nitrate using green amaranth leaf extract as a reducing agent. The degradation of caffeine and inactivation of Escherichia coli (E. coli) by Ag2O-NPs was studied under compact fluorescent lamp illumination irradiation. Apart from that, the antibacterial and antioxidant activities of Ag2O-NPs were also examined. Synthesized Ag2O-NPs were shaped like monodispersed husk, and cubic structured with surface area, and average particle size was detected to be 100.21 (m2/g) and 81 nm, respectively. Antioxidant efficacy of the Ag2O-NPs was evaluated using 1, 1-diphenyl-2-picrylhydrazyl, and 91% inhibition was achieved with 100 µg Ag2O-NPs. Cell viability assay demonstrated that Ag2O-NPs showed less cytotoxicity for human embryonic kidney (HEK 293) cells. The bacteriocidic propensity of Ag2O-NPs was examined against the S. aureus and P. aeruginosa by disk diffusion, minimum inhibitory concentration (MIC), live and dead assay. It was observed that the NPs have a higher bactericidal effect on Gram-negative as compared to Gram-positive bacteria. Up to 96%, photocatalytic inactivation of E. coli was achieved using 30 µg/mL of NPs. Photocatalytic degradation of caffeine (50 ppm initial concentration) was observed to be 99% at pH 9 in 15 h using 50 mg/L of Ag2O NPs. These results indicate that Ag2O NPs can be employed in environmental applications like harmful bacteria inactivation and organic pollutants degradation. Graphic abstract: [Figure not available: see fulltext.]