Multivalent polymer-Au nanocomposites with cationic surfaces displaying enhanced antimicrobial activity

Pathogenic bacteria pose a catastrophic threat to human health worldwide. Herein, cationic polymer-functionalized gold nanoparticles were synthesized via the reduction of chloroauric acid in the presence of cationic polymers as multivalent inhibitors of pathogenic bacteria. The cationic polymers were prepared by reversible addition-fragmentation chain transfer polymerization and the tertiary amino groups of the polymers were quaternized to improve their antimicrobial activity. These nanocomposites had large concentrations of positive charge, which promoted their adsorption onto negatively charged bacterial membranes through electrostatic interactions. Through a study of their antibacterial properties, it was observed that these nanocomposites with multivalent antibacterial effects could rapidly and efficiently kill Gram-positive and Gram-negative bacteria. Morphological changes observed via scanning electron microscopy confirmed that the synthesized nanocomposites caused disruption of the cytoplasmic membrane and leakage of cytoplasm. This novel antimicrobial material with effective antibacterial activity and better biocompatibility can promote the healing of bacteria-infected wounds and has promising applications in the biomedical field.