Facile synthesis and characterization of cross-linked chitosan quaternary ammonium salt membrane for antibacterial coating of piezoelectric sensors

Novel cross-linked chitosan quaternary ammonium salt (CHACC) membranes were successfully prepared by the reaction of chitosan quaternary ammonium salt (HACC) and epichlorohydrin. The structures and morphologies of the CHACC membranes were characterized. The water stability and antibacterial efficiency of CHACC membranes were investigated by the equilibrium swelling method, the plate count method and minimum inhibitory concentration (MIC) test, respectively. Further, an antibacterial piezoelectric sensor with a multilayered structure was prepared by attaching the CHACC membrane to a poly(vinylidenefluoride‑co‑trifluoroethylene) (PVDF-TrFE) based sensor. The piezoelectrical properties of PVDF-TrFE based sensors coated with CHACC were investigated. The results showed that the CHACC-4 with a three-dimensional network structure exhibited best water stability (193% of swelling degree) and antibacterial properties (antibacterial rate > 99%), and the MIC of CHACC against E. coli, S. aureus and P. aeruginosa was 40, 320 and 640 μg/mL, respectively. Additionally, the coating of CHACC-4 had no adverse effect on the piezoelectric properties of the prepared sensor. The fabricated multilayer sensor has potential applications in the field of wearable devices.