Synthesis, characterization and antimicrobial activities of water-soluble amphiphilic copolymers containing ciprofloxacin and quaternary ammonium salts

A series of novel water-soluble amphiphilic copolymers containing ciprofloxacin (CPF) and quaternary ammonium salts were prepared by the free-radical copolymerization of methacrylate monomers with CPF, quaternary ammonium salt (QAS) monomers and butyl acrylate (BA). The copolymers were characterized by 1H-NMR, charge density and UV measurements. The antimicrobial activities of the copolymers, based on the minimum inhibition concentration (MIC) against Escherichia coli (E. coli), varied with hydrophobic BA content in the copolymers. The incorporation of the antimicrobial moiety ciprofloxacin further enhanced the antibacterial activities of the copolymers, reducing the MIC to 4.0 ppm. The UV260 absorption measurements were applied to reveal the dynamic antimicrobial process of the copolymers. The results of inhibition zones and shaking flask methods of antimicrobial-modified fibers showed that the copolymers had excellent antimicrobial activities when applied to cellulose fibers. In the presence of 2 wt% (based on oven-dried fibers) of the copolymer, the growth inhibition reached 100%.