pH-responsive spiropyran-based copolymers and their application in monitoring and antibacterial coatings

Abstract Although many multifunctional antibacterial materials have been developed, there are few antibacterial materials that can simultaneously monitor pathogenic bacteria and sterilize efficiently. In this work, pH-responsive spiropyran-based fluorinated copolymers with antibacterial, antifouling and fluorescence performances were prepared. First, the random copolymer of methacrylic acid and 1H,1H,2H,2H-perfluorododecyl acrylate (P(MAA-co-FDA)) were synthesized by RAFT polymerization. Second, spiropyran (SP) was grafted onto P(MAA-co-FDA) to obtain the P(MAA-co-SP-co-FDA) copolymer with fluorescence property. At the third step, the remaining carboxyl groups in the grafted copolymer were complexed with protonated polyhexamethylene biguanidine salt (PHMB) to obtain the P(MAA-co-SP-co-FDA)/PHMB copolymer complex antibacterial materials. The results show that the copolymer complex coatings can effectively inhibit the adhesion of bacteria and release PHMB in a bacterial microenvironment to kill S. aureus and E. coli but remain noncytotoxic. The P(MAA-co-SP-co-FDA) copolymer or its complex with PHMB can open the ring and generate a red fluorescence under acidic conditions produced by bacterial growth and metabolism. In addition, the coatings have good biocompatibility, which may be suitable for medical devices to reduce bacterial infection in vivo and in vitro. The prepared multifunctional materials with excellent anti-adhesion, antimicrobial and fluorescence characters will have a broad application prospect in antibacterial, antifouling and monitoring of medical devices.