Dual-Function Polymer-Silver Nanocomposites for Rapid Killing of Microbes and Inhibiting Biofilms

Polymer-silver nanocomposites have emerged as an integral weapon to combat device-related infections. However, synthesis of the nanocomposites still remains a major challenge that often involves two-step process in which silver nanoparticles are synthesized ex situ. Additionally, polymers used in the nanocomposites are commonly not antimicrobial and biodegradable thus often lack bioactivity and biocompatibility. Herein we report highly active dual-function polymer-silver nanocomposites consisting of an inherently antimicrobial and biodegradable polymer in one-pot. A simple method of in situ reduction of a silver salt was employed to synthesize the silver nanoparticles (5-15 nm) from silver para-toluenesulfonate in which the intrinsically biodegradable and antimicrobial polymer N,N-dimethyl-N-hexadecyl ammonium chitin tosylate acted as reducing as well as stabilizing agent. The nanocomposite with the water-insoluble and organo-soluble polymer was simply painted onto surfaces via facile noncovalent immobilization. Notably, composite-coated surfaces inactivated both drug-sensitive and drug-resistant bacteria including pathogenic fungi at a much faster rate than polymer alone. The composites released active silver ions over an extended period of time and displayed remarkably long-lasting activity. In addition, surfaces coated with composites effectively inhibited both bacterial and fungal biofilm formation. Further, upon coating on catheter, the nanocomposites reduced methicillin-resistant Staphylococcus aureus (MRSA) burden both on catheter (>99.99% reduction) and in tissues surrounding the catheter (>99.999% reduction) in a mice model. These novel nanomaterials that showed negligible hemolysis toward human erythrocytes might be used as safe and effective antimicrobial coatings in biomedical device applications.