The grafting of chitosan oligomer to polysulfone membrane via ozone-treatment and its effect on anti-bacterial activity

Polysulfone (PSF) membranes were treated with ozone to introduce peroxides, and then grafted with acrylic acid, followed by the coupling of chitosan oligomer. Water soluble chitooligosaccharides (COS) was prepared to induce antimicrobial activities. The surface densities of the carboxylic and amino groups on the PSF membranes were characterized by dyeing determination and the hydrophilicity was evaluated by the contact angle. The antibacterial activities on the PSF membrane were evaluated based on a viable cell counting method. The results show that COS can be covalently bound to the surface of PAA-grafted PSF membrane via the activation of 1-ethyl-3-dimethylaininopropyl carbodiimide (EDC). The water contact angle was lower for the PAA-grafted and COS-coupled PSF, indicating that they were more hydrophilic than the untreated PSF membrane. Only COS-coupled PSF membrane showed a strong biocidal effect for bacteria, including E. coli and S. aureus.