Biogenic synthesis, optimization, and characterization of novel silver nano particle using combined seed extracts

Abstract

This study explores the biogenic synthesis, optimization and characterization of silver nanoparticles (AgNPs) using plant-derived extracts from black seed, neem seed, and baobab seed. The synthesis of nanoparticles was optimized using the Taguchi response method and the optimized condition was used for the synthesis which was confirmed by UV-Vis spectroscopy, which revealed a distinct surface plasmon resonance (SPR) peak at 413 nm. The FTIR spectra for AgNPs exhibited characteristic bands at 566.56, 1028.75, 1394.02, 1632.57, and 3220.42 cm⁻¹, indicating metal-ligand interactions such as Ag-O and Ag-N bonds, suggesting the involvement of plant-derived compounds like polyphenols and amino acids in stabilizing the nanoparticles. XRD analysis confirmed the crystalline nature of the nanoparticles with characteristic diffraction peaks at 32.31, 47.24, 55.22, 68.90, 77.78, and 86.37°. The average particle size of the AgNPs was found to be 38.51nm. SEM analysis revealed the nanoparticles shape, and the AgNPs were found to possess a hexagonal shape. Elemental analysis from EDX confirmed the presence of silver in the nanoparticles showing 50.4% Ag alongside C, O, and other elements from plant-derived capping agents. Antimicrobial testing revealed the specific activity of the nanoparticle against various pathogens. AgNPs demonstrated good antibacterial activity, with significant inhibition observed against Staphylococcus aureus (23 mm), Escherichia coli (22 mm), and fungi. These findings highlight the potential of plant-derived nanoparticles as effective antimicrobial agents, with the silver nanoparticles being particularly effective against both Gram-positive and Gram-negative bacteria and fungi.