Combating multidrug-resistant bacteria with nanostructured guanidine-based polymers

Abstract

Traditional antibiotics have specific intracellular targets and disinfect in chemical ways, and multi-drug resistance induced by antibiotics has become an emerging threat to human health. Therefore, it is urgent to develop novel antibacterial agents to combat multi-drug resistance. Herein, we report a new antibacterial nanocomposite (PGH@AgNPs), which was prepared by decorating polymeric guanidine hydrochloride with silver nanoparticles (AgNPs). The Ce(IV)/pentaerythritol redox system was used to initiate the polymerization of a vinyl monomer, guanidine hydrochloride (GH), to prepare star-shaped polymerized GH (PGH), which was then decorated with silver nanoparticles (AgNPs). The physicochemical properties of the nanocomposite were characterized using UV, SEM, XPS and XRD. The biological assays revealed that the nanocomposite possessed effective broad-spectrum antibacterial properties, showing the minimum inhibitory concentrations (MICs) ranging from 6 to 12 µg mL⁻¹, a sterilization rate of higher than 90%, and MIC values of 8, 12 and 12 µg mL⁻¹ against the clinically isolated drug-resistant bacteria MRSA (TACC43300), VRE and P. aeruginosa, respectively. Particularly, S. aureus and P. aeruginosa treated with PGH@AgNPs did not develop drug resistance even after 21 passages because PGH@AgNPs could irreversibly damage the bacterial membrane structure and induce the generation of reactive oxygen species (ROS), ultimately killing the bacteria. In addition, PGH@AgNPs exhibited high blood biocompatibility in mouse fibroblast cells (L929). Overall, PGH@AgNPs has great potential to be used as an antibacterial material with high cytocompatibility for the control of multi-drug-resistant bacterial infections.