Mentha aquatica leaf extract mediated phytosynthesis of silver nanoparticles: antioxidant, catalytic and anti-microbial activity

Abstract

The present contribution reports a simple and environmentally friendly method of synthesizing silver nanoparticles (AgNPs) using the aqueous leaf extract of Mentha aquatica. The impacts of different operational parameters such as leaf extract dosage, pH solution, temperature and contact time on the formation of AgNPs were examined in detail. The data revealed that 5% v/v Mentha aquatica leaf extract, pH value 9.0, temperature 18 °C and 60 min reaction incubation time results in the optimum nanoparticle synthesis. The as-formed AgNPs were analyzed by (UV-Vis), FT-IR, X-ray diffraction (XRD), SEM/EDX and TEM. The FT-IR analysis demonstrated the involvement of phytochemicals in the synthesis of AgNPs. The TEM images indicated the mainly spherical forms of the AgNPs with a mean particle size of 25 nm. The XRD spectrum confirmed the face-centered cubic structure for the AgNPs. Additionally, in the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical antioxidant study, the antimicrobial properties against Gram-positive and Gram-negative pathogens and the catalytic activity of the obtained silver nanoparticles were investigated. The results showed that the nanoparticles presented promising antioxidant and antibacterial activities. Moreover, significant catalytic activity in degrading Methylene blue (MB) with a maximum degradation capacity of up to 98% at a 2 mg catalyst dose was also observed. Hence, an easy and simple green approach for the synthesis of silver nanoparticles, with efficient antioxidant and antimicrobial properties and catalytic degradation of MB dye is reported in this study.