Research On Improving The Surface Hemocompatibility Of Polydimethyl Siloxane Elastomer

Biocompatibility of biomaterials is the unique property that makes them different from other functional materials, and hemocompatibility is the crucial factor that determines whether the biomaterials could be applied to the blood-contact medical devices. When biomaterials contact with blood, the competitive adsorption of various plasma proteins is the first to take place. The protein layer thus formed is the main reaction site between blood and biomaterials. The variety, quantity and adsorption state of absorbed proteins on biomaterials are important factors that determine subsequent biological reactions, such as platelet adhesion. These factors, however, are affected by the surface property of biomaterials. So, manipulating the surface properties of biomaterials, thereby controlling the adsorption behavior of proteins, is the key to deal with the issue of biomaterials' hemocompatibility.In this study, the common biomaterial-polydimethyl siloxane (PDMS) elastomer was used as the substrate, and a biologically inert surface was first obtained which can resist nonspecific protein adsorption; Bioactive molecules were then incorporated onto these surfaces, which could selectively adsorb plasminogen to activate fibrinolytic channel, and to achieve the thrombolytic purpose. Details are as follows:(1) First, the path of functionalizing polydimethyl siloxane elastomer surface is optimized, so that a high-density silicon-hydrogen bonding surface is formed, and the hydrophilic allyl-glucopyranose and allyl-polyethylene glycol can be grafted to the surface by hydrosilylation,. Hydrophilic and protein-resistant adsorption tests show that: the two substances could increase surface wettability, but the surface grafted with polyethylene glycol has a much better protein-resistant adsorption capacity. In contrast, the surface grafted with glucopyranose tends to adsorb large amount of protein. Based on these two aspects, the surface grafted with PEG will have a better antithromgenic effect.(2) To activate the ends of polyethylene glycol grafted on the surface by attaching amino acid which is able to selectively adsorb protein. Polyethylene glycol is particularly effective in minimizing nonspecific protein adsorption, and the lysine at the end of polyethylene glycol can selectively couple plasminogen. Test results indicate that the surface can effectively dissolve newborn fibrin clots. Combining the "passivation" and "activation" concepts to construct a surface with special antithrombus activity is a major innovation of this research.In summary, the blood compatibility of the polydimethyl siloxane elastomer was improved by chemical modification of the material's surface, and thereby the manipulation of protein adsorption on the surface. This study not only establishes the theoretical foundation for blood compatibility of materials, but also provides a new idea for the design of new biomaterials.