Synthèse et activité biologique de nano-composite à base des nanoparticules d’argent

Abstract

This contribution reports a simple and environmentally friendly method for synthesizing silver nanoparticles (AgNPs) using aqueous leaf extract of Mentha aquatica. The impacts of various operational parameters such as leaf extract dosage, solution pH, temperature, and contact time on the formation of AgNPs were examined in detail. Data revealed that 5% v/v Mentha aquatica leaf extract, a pH of 9.0, a temperature of 18°C, and an incubation time of 60 minutes yielded optimal nanoparticle synthesis. The resulting AgNPs were analyzed using UV-Vis spectroscopy, FT-IR, and X-ray diffraction (XRD). TEM images showed that the AgNPs were predominantly spherical, with an average particle size of 25 nm. Furthermore, the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay was used to study the antimicrobial properties against Gram-positive and Gram-negative pathogens and the catalytic activity of the synthesized silver nanoparticles. The results demonstrated that the nanoparticles exhibited promising antioxidant and antibacterial activities. Additionally, significant catalytic activity in the degradation of methylene blue (MB) was observed, with a maximum degradation capacity of up to 98% at a catalyst dose of 2 mg. Therefore, a simple and easy-to-implement green approach for the synthesis of silver nanoparticles with high degradation capacity is presented. Hexagonal mesoporous silica MCM-41 is one of the commonly used hosts for incorporating silver nanoparticles, providing pore channels suitable for confining ultrafine metal nanostructures within its channels. Ag nanoparticles were confined inside the pore channels of MCM-41 by an in situ biological reduction method. XRD and FTIR were used to characterize the MCM41-AgNPs composites. These MCM41-AgNPs catalysts showed excellent catalytic activity for dye removal compared to its absence in the reaction medium, with the plasmon band position between 650 and 675 nm.