One-Step Green Preparation of Monodisperse Silver-Lignin Nanocomposites Via Poly-L-Lysine Co-Assembly to Mitigate Antibiotic Resistance

Abstract

Monodisperse nano/microstructures offer significant potential as carriers for metal nanoparticles (NPs) because of their enhanced catalytic activity, derived from their large surface area. Notably, the development of a one-step in-situ reduction method for NP synthesis, combined with carrier fabrication, has attracted attention because of its environmentally friendly and sustainable approach. Herein, we demonstrate that poly-L-lysine (PL) regulates the self-assembly kinetics of kraft lignin (KL), efficiently reducing silver ion (Ag+) to silver nanoparticles (AgNPs) without the necessity for chemical reducing agents. This process resulted in the formation of AgNPs integrated into highly monodisperse co-self-assembled PL-KL particles (Ag@PL-KLPs). PL facilitated rapid KL desolvation, promoting intermolecular interactions and silver ion adsorption, followed by an efficient, separate nucleation and growth process. Additionally, PL, acting as a steric stabilizer, yielded Ag@PL-KLPs which were approximately 270 nm in size with a narrow distribution. Notably, Ag@PL-KLPs exhibited potent bactericidal properties against antibiotic-resistant bacteria (ARB), including both Gram-negative and -positive strains, inhibiting bacterial growth and killing at concentrations ranging from 250 to 500 μg/mL. Leveraging the abundant, biomass-derived lignin and the cost-effective nature of this one-step green synthesis approach could provide a sustainable method for the production of noble metal-based nanocomposites, with promising applications across a broad spectrum.

Keywords: Kraft lignin, Poly-L-lysine, Self-assembly, green fabrication, Antibiotic-resistant bacteria, Bactericidal