ε-Poly- l -lysine-Functionalized 2D MoS2 Nanosheets for Photothermal Inhibition of Cold-Adapted Shewanella putrefaciens

Abstract

Psychrotrophic Shewanella putrefaciens, notorious for dominating cold chain spoilage through cold-adapted membrane dynamics and robust biofilm formation, challenges conventional antimicrobial strategies that lose potency under refrigeration and raise food safety concerns. We report an engineering approach that transforms ε-poly-l-lysine (ε-PL), a GRAS-listed food preservative, into a triple-duty agent: a green exfoliant for MoS2 nanosheets, a cationic surface modifier, and a synergistic antimicrobial partner. The engineered ε-PL@MoS2 nanosheets exploit a unique vulnerability of cold-adapted bacteria, where their fluidized membranes rich in unsaturated phospholipids become prime targets for ε-PL’s high-density positive charges (pKa∼10.5), which induce deep penetration and disruption. NIR-triggered mild hyperthermia (40 °C) amplifies this effect by destabilizing lipid phase transitions, accelerating membrane damage, and triggering protein leakage, creating a physicochemical dual-strike mechanism that achieves exceptional bactericidal performance (5.2-log CFU reduction) and near-complete biofilm removal (99.7%) within 10 min at room temperature. This intelligent, food-safe nanoplatform bridges nanoscience and cold chain preservation, offering a clean-label solution to combat antibiotic-resistant psychrotrophic pathogens.