Phytosynthesis, characterization of silver nanoparticles using Pentapetes phoenicea leaf extract and their antimicrobial effects on some food pathogens
摘要
The AgNPs used for this work were obtained from ethanolic extract of Pentapetes phoenicea leaves and AgNO3 via the green synthesis method (natural reducing agent), which are found in a dark brown colour, which is attributed to the reduction reaction of Ag+ ions to Ag0. As determined by TEM and XRD analyses, the nanoparticle size ranges from 10 to 40 nm and exhibits an approximately spherical morphology. The ethanolic extract of P. phoenicea, analysed through phytochemical screening, contains metabolites that act as reducing and stabilizing agents. Silver nanoparticles were formed by reacting the 5% ethanol extract at pH 12 for 15 min, resulting in an SPR peak at 403 nm. UV–Vis analysis over 2 days showed that the SPR peak remained stable between 400 and 403 nm. FTIR analysis shows silver nanoparticles’ reduced absorption peak spectrum at a wave number of 760 cm−1. The XRD and TEM results show that silver nanoparticles have an average crystal size of 17.9 ± 2.03 nm. Silver nanoparticles have a spherical shape with an average particle size of 18 nm, which can be seen in the TEM results’ morphology. The silver nanoparticles synthesized with a low concentration of P. phoenicea extract demonstrated stronger inhibition of E. coli (MIC: 0.41 µg/mL, MBC: 1.2 µg/mL) than S. aureus (MIC: 0.20 µg/mL, MBC: 0.6 µg/mL). A delayed bactericidal effect was observed, with time-dependent inhibition noted through colony-forming unit counts at various intervals. While AgNPs are promising antibacterial agents for food-related applications, potential cytotoxicity to human cells or animals must be considered. Thus, AgNPs from P. phoenicea leaf extract show potential as an antibacterial agent against food-pathogenic bacteria.