Copper(ii)-based coordination polymer nanofibers as a highly effective antibacterial material with a synergistic mechanism

Abstract

Nanofibers of a copper(II)-based coordination polymer [Cu(HBTC)(H₂O)₃] were synthesized via a microwave-assisted hydrothermal process, while macroparticles and bulk crystals were prepared via a hydrothermal method. X-ray analysis revealed that this compound possesses one-dimensional zig-zag chains, in which the coordination polyhedron of the copper(II) center is a five-coordinate distorted square-pyramid. The width of the as-prepared nanofibers was about 150 nm, while the size of the macroparticles was about 200 μm. The antibacterial activities of the nanofibers and macroparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated by determining the minimal inhibitory concentration (MIC), the growth curve of the bacteria and the bacterial reduction assay. The nanofibers showed higher antibacterial performance as compared with macroparticles, commercial copper nanoparticles, and pure ligands alone. The bacteriostatic rates of nanofibers and macroparticles were up to 99.9% and 96.7% against E. coli, while 99.1% and 96.2% against S. aureus, respectively, when the concentration was 250 μg mL⁻¹. The synergistic antibacterial mechanism was also proposed based on the generation of reactive oxygen species (ROS) and the release of Cu²⁺ ions.