A p-vinylbenzyl sulfobetaine was grafted from cellulose membrane (CM) using surface-initiated atom transfer radical polymerization for blood compatibility improvement. Surface structure, wettability, morphology, and thermal stability of the CM substrates before and after modification were characterized by attenuated total reflectance Fourier transform infrared spectra, X-ray photoelectron spectroscopy measurement, water contact angle measurement, atomic force microscopy, and thermogravimetric analysis, respectively. The results showed that zwitterionic brushes were successfully fabricated on the CM surfaces, and the content of the grafted layer increased gradually with the polymerization time. The blood compatibility of the CM substrates was evaluated by protein adsorption tests and platelet adhesion tests in vitro. It was found that all the CMs functionalized with zwitterionic brush showed improved resistance to nonspecific protein adsorption and platelet adhesion, even though the grafting polymerization was conducted for several minutes.

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Silicone rubber has been used as a biomaterial for more than two decades and displays good mechanical and optical properties, but its chemical nature, poor antithrombogenicity, as well as its hydrophobicity, prevents its use in many demanding biomedical applications. In order to provide modified silicone with enhanced haemocompatibility, surface modification techniques were used. Ozonization was used to introduce active peroxide groups onto the silicone film surface and, subsequently, graft polymerization of N,N -dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium (DMMSA), a zwitterionic sulfobetaine structure, onto the ozone activated silicone surface was conducted. Surface analysis was accomplished by means of attenuated total reflectance-Fourier-transform infrared (ATR-FTIR), and X-ray photoelectron spectra (XPS), and scanning electron microscopy (SEM) and contact angle measurement. ATR-FTIR and XPS investigation confirmed the graft polymerization. The grafted film possessed a relatively hydrophilic surface as indicated by contact angle measurement. The blood compatibility of the grafted films was evaluated by platelet adhesion in platelet-rich plasma (PRP) and protein adsorption in bovine fibrinogen using silicone film as the reference. No platelet adhesion was observed for the grafted films incubated in PRP for 120 min. The protein adsorption was reduced on the grafted films after incubated in bovine fibrinogen for 120 min. These results confirmed that the improved blood compatibility was obtained by grafting this new zwitterronic sulfobetaine structure onto silicone film.