Biologically inert (Bio inert) materials play a major role in the development of medical devices. These materials when introduced to biological tissues do not cause any reaction with the host. These materials find its way in many medical applications such as in vascular surgery, bone treatments, and cardiac pacemakers. The hydrogen bonds in the non-functional fouling groups produce a structured water layer, which serves as a strong hydrogen barrier.
The available zwitterionic modifications fail to provide a universal surface grafting solution for the coating of medical devices. Group of researchers from Taiwan led by Professor Yung Chang from Chung Yuan Christian University developed a robust antifouling grafting method for the generation of zwitterionic interfaces on versatile surfaces such as ceramic, polymer, silicon wafer, steel etc. Polyethylene glycol is widely studied for its non-fouling behavior. When polyethylene glycol is used in medical devices, it produces durability problems. This is due to the decomposition of oxidized chemicals.
Sulfobetaine and phosphobetaine are some of the zwitterionic materials being used nowadays. Sulfobetaine methacrylate is widely used because of its low cost and is highly compatible with biological field. Poly(sulfobetaine methacrylate) provides resistance to blood cell attachment, bacterial attachment and human tissue adhesion. Providing resistance is one of antifouling performances. The resistance is due to the ability of the Poly(sulfobetaine methacrylate) to form an ultra-hydrophilic interface.
Switchable zwitterion, thermo-responsiveness, hydrophobic anchoring and ionic pairing are some of the extended features of Poly(sulfobetaine methacrylate) which have been developed. Even though zwitterionic materials provide good fouling resistance, modifying the versatile substrates and other bio material surfaces is still a difficult process. Hence a grafting form method is developed by the team of authors for the generation of antifouling stealth surface. Surface induced atom transfer radical polymerization (SI-ATRP) is the process by which the stealth surface is generated.
Improvements can be made by incorporating the formation of covalent bonds in the ‘grafting to’ strategy. The molecular weight of prefabricated sulfobetaine copolymers needs to be controlled. In this paper, the versatile surface is coated using ‘grafting to’ method as it is an effective and economical method. A stable chemisorption coating is made on the versatile surfaces. The ring opening reaction between the polymer epoxide end groups and substrate hydroxyl groups provides a strong reactivity while accelerated by applying triethylamine in the coating system. The results also showed that the basic catalyzation by triethylamine is essential to achieve sufficient antifouling surface
The authors used ImagePro 7.0 software to count the cells of attached blood cells and tissue cells. The cells are counted from the fluorescence images. For three different areas, the counting was repeated and the data are analyzed. Twelve copolymers were prepared on a random basis and they are coated in the silicon substrates. The coating conditions and the compositions were examined for the copolymers. The hydrophilicity of the copolymer-coated surfaces is indicated from the water contact angle.
Protein adsorption occurs when hydrophobic segments interact with protein hydrophobic patches. The surface grafting coverage can be regulated by controlling the parameters (copolymer concentration and the amount of trimethylamine catalyst). The bio-fouling components were tested on the substrates. The blood components in the body, such as platelets and erythrocytes generate necessary signals to sustain the normal homeostasis.
The versatile surface grafting method with biofouling resistance, developed by the authors provides an efficient way in the application of stealth biomaterial interfaces. The antifouling requirement is achieved by grafting the new zwitterionic sulfobetaine based copolymer on the versatile biomaterials. This proposed method of the authors offers a new opportunity in next generation medical devices.
Ying-Nien Chou1, Ten-Chin Wen1, Yung Chang2,3, Zwitterionic surface grafting of epoxylated sulfobetaine copolymers for the development of stealth biomaterial interfaces, Acta Biomaterialia, Volume 40, 2016, Pages 78-91.Show Affiliations
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
- R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chung-Li, Taoyuan 320, Taiwan.
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
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