Study On Co-Immobilizing Heparin And Selenocystamine On TiO₂Films Surface To Improve Blood Compatibility

Nitric Oxide was the most important signal molecule of cardiovascular system and always generated by vascular endothelial cells. Relative researches showed that NO donor containing materials could enhance the anti-thrombosis property and contribute to biomedical use. In combination with the powerful anticoagulation performance of heparin and the favorable ability of selenocystamine in catalytic the release of in situ endogenous NO, this paper constructed a catalytic activity layer by covalent immobilization of heparin and selenocystamine on the surface of titanium oxide film materials to improve blood compatibility.The TiO2film was firstly deposited on silicon (100) wafers using an unbalanced magnetron sputtering system. Then, a polydopamine coating was prepared onto the TiO2film material surface as an organic linker (hydroquinone and amino, etc). The carboxyl group of heparin was activated by EDC/NHS/MES and subsequently immobilized on the dopamine coated surface, and then the selenocystamine that containing amino group was immobilized on the dopamine surface via Michael addition or Schiff base reaction. FTIR and XPS results confirmed that the molecules were successfully immobilized on DM coated surfaces. Amino quantitative results showed that the density of amino on DM coated surface is about15.53n mol/cm2. The quantitive measurement results from QCM-D indicated that the amount of immobilized heparin was about297.3ng/cm2, and the immobilized selenocystamine was about670.5ng/cm2.The biological evaluation results showed that the enzyme activity of the modified sample of TDHSe was about33.75U/cm2. The result of in vitro platelet adhesion test showed that the platelet quantity on sample surface modified by the heparin and selenocystamine was less than that on the controlled TiO2film sample surface with no NO donor condition. Meanwhile, for the SNAP donor group, the platelet adhesion, activation and gather on the TDHSe samples surface had been significantly inhibited due to the joint action of heparin and NO. Additionally, the result of cGMP test confirmed that the anticoagulation property was derived from the NO-cGMP signaling pathways. In summary, a catalytic activity layer was successfully constructed onto the TiO2film surface by using molecules of heparin and selenocystamine in this work. The catalytic activity layer could catalyze the release of NO from endogenous NO donor. Biological compatibility evaluation results showed that the anticoagulation performance was improved due to the double effects of the heparin and NO releasing.