A facile and greener approach for synthesis of lignin capped-silver nanoparticles (LS-AgNPs) and assessment of their antibacterial and antioxidant properties

Abstract

Silver nanoparticles have garnered significant attention in research due to their numerous advantageous qualities, such as antimicrobial, antioxidant, and anticancer activities. Several methods have been employed previously to produce these nanoparticles, but green synthesis has gained prominence due to its lack of harmful by-products. In this study, stable and biocompatible lignin-capped silver nanoparticles (LS-AgNPs) have been synthesized using a green approach that utilized nontoxic sodium lignosulfonate as both the reducing and capping agents. Various process parameters, such as pH, temperature, time, and raw material concentration have been optimized to simplify, accelerate and mould the synthesis activity easy and eco-friendly. The morphology and dimensions of the prepared lignin-capped silver nanoparticles (LS-AgNPs) have been characterized using UV–Vis spectroscopy, particle size analyser, X-ray diffraction analysis, Fourier transform infrared spectroscopy and Transmission Electron Microscopy. The produced nanoparticles have an average diameter of 24 nm and a FCC crystalline structure that is capped with lignin components. MBC of LS-AgNPs has been found 4 and 6 ppm against S. aureus and E. coli bacteria, respectively. The IC50 value for antioxidant property has been found 34.37 μg/mL. In summary, the prepared LS-AgNPs have exhibited a synergistic effect resulting from the combination of lignosulfonate and silver particles. The synergistic effect not only enhances antimicrobial activity and antioxidant property remarkably, this approach enables the utilization of biobased silver nanoparticles for various applications with its requirement of minimal quantity to have much lowered toxicity compared to pure silver nanoparticles.