| Reversible addition-fragmentation chain transfer (RAFT) polymerization has been widely used to synthesize or modify different polymeric materials such as constructing polymer brushes on different kinds of material surface. Cellulose is a widely used natural polymer material. It is not only one of the most abundant natural polymers in the world, but also an inexpensive and renewable biomedical material. However, the blood compatibility of raw cellulose is inadequate and needs to be improved before use. In recent years, zwitterionic materials which contain both anionic and cationic units in the same molecule are extremely attractive as a class of materials with excellent blood compatibility and antifouling property. So in this work, we aimed to graft the sulfobetaine brush from cellulose membrane (CM) via Surface Initiated RAFT (SI-RAFT) polymerization for blood compatibility improvement.The effect of grafting time and monomer concentration on the grafting amount and blood compatibility were studied. Characterization of the CM substrates before and after modification was carried out by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetry (TG), water contact angle measurements, X-ray photoelectron spectroscopy analysis (XPS), and atomic force microscopy (AFM), respectively. The results demonstrated that zwitterionic brushes were successfully grafted on the CM surfaces, and the content of the grafted layer increased gradually with monomer concentration and the polymerization time.The platelet adhesion, hemolytic test and plasma protein adsorption results indicated that the grafted cellulose membrane had improved resistance to nonspecific protein adsorption and platelet adhesion, as well as reduced hemolysis rate comparing to pristine cellulose. The zwitterionic brush functionalized cellulose which showed excellent blood compatibility will have greater potential for biomedical applications. |
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