Amino acid-conjugated polymer-silver bromide nanocomposites for eradicating polymicrobial biofilms and treating burn wound infections

Abstract

The rise in antimicrobial resistance, the increasing occurrence of bacterial, and fungal infections, and the challenges posed by polymicrobial biofilms necessitate the exploration of innovative therapeutic strategies. Silver-based antimicrobials have garnered attention for their broad-spectrum activity and multimodal mechanisms of action. However, their effectiveness against single-species or polymicrobial biofilms remains limited. In this study, we present the fabrication of polymer-silver bromide nanocomposites using amino acid conjugated polymers (ACPs) through a green and water-based in situ technique. The nanocomposite architecture facilitated prolonged and controlled release of the active components. Remarkably, the nanocomposites exhibited broad-spectrum activity against multidrug-resistant (MDR) human pathogenic bacteria (MIC = 2–16 μg/mL) and fungi (MIC = 1–8 μg/mL), while displaying no detectable toxicity to human erythrocytes (HC₅₀ > 1024 μg/mL). In contrast to existing antimicrobials and silver-based therapies, the nanocomposite effectively eradicated bacterial, fungal, and polymicrobial biofilms, and prevented the development of microbial resistance due to their membrane-active properties. Furthermore, the lead polymer-silver bromide nanocomposite demonstrated a 99% reduction in the drug-resistant Pseudomonas aeruginosa burden in a murine model of burn wound infection, along with excellent in vivo biocompatibility.