Solvent-Induced Lignin Conformation Changes Affect Synthesis and Antibacterial Performance of Silver Nanoparticle

The emergence of antibiotic-resistant bacteria necessitates the development of novel, sustainable, and biocompatible antibacterial agents. This study addresses cytotoxicity and environmental concerns associated with traditional silver nanoparticles (AgNPs) by exploring lignin, a readily available and renewable biopolymer, as a platform for AgNPs. We present a novel one-pot synthesis method for lignin-based AgNPs (AgNPs@AL) nanocomposites, achieving rapid synthesis within 5 min. This method utilizes various organic solvents, demonstrating remarkable adaptability to a wide range of lignin-dissolving systems. Characterization reveals uniform AgNP size distribution and morphology influenced by the chosen solvent. This adaptability suggests the potential for incorporating lignin-loaded antibacterial drugs alongside AgNPs, enabling combined therapy in a single nanocomposite. Antibacterial assays demonstrate exceptional efficacy against both Gram-negative and Gram-positive bacteria, with gamma-valerolactone (GVL)-assisted synthesized AgNPs exhibiting the most potent effect. Mechanistic studies suggest a combination of factors contributes to the antibacterial activity, including direct membrane damage caused by AgNPs and sustained silver ion release, ultimately leading to bacterial cell death. This work presents a straightforward, adaptable, and rapid approach for synthesizing biocompatible AgNPs@AL nanocomposites with outstanding antibacterial activity. These findings offer a promising and sustainable alternative to traditional antibiotics, contributing to the fight against antibiotic resistance while minimizing environmental impact.