Quaternary ammonium salt (QAS)-modified thermoresponsive PNIPAM-PDMAEA copolymer for antibiofilm and antimicrobial applications

The development of antimicrobial and antibiofilm materials for treating bacterial pathogens is attracting considerable research attention. Polymers with specific functionalities play important roles in the preparation of antimicrobial materials. In this study, a novel copolymer with dual functions was synthesized. A one-pot copolymerization technique was used to copolymerize N-isopropylacrylamide (NIPAM) and 2-dimethylaminoethylmethacrylate (DMAEA) monomers and quaternized them with alkyl bromide to produce thermoresponsive poly (N-isopropylacrylamide) (PNIPAM) segments. These PNIPAM segments exhibited high-efficient antimicrobial and antibiofilm properties of quaternary ammonium salt (QAS)-based PDMAEMA segments together in a single copolymer system. The synthesized PNIPAM-DMAEMA (CP- 9:1, 8:2, 7:3, 6:4, and 5:5) copolymer-QAS (QAS- C4, C6, and C8) were characterized using a range of techniques. Among them, PNIPAM-DMAEMA-7:3@QAS-C4 copolymer (CP-7:3@QAS-C4) at 100 μg/mL inhibited biofilm formation by fungal Candida albicans via impeding hyphal formation. In addition, CP-7:3@QAS-C4 and CP-7:3@QAS-C6, at 100 μg/mL markedly inhibited single biofilm formation by uropathogenic Escherichia coli (UPEC) and multispecies biofilm development by UPEC and C. albicans. Overall, a novel synthetic method was developed for producing QAS-based antimicrobial copolymers with potential antibiofilm efficiency that could be applied in biomedical applications.