Immobilization Of Chiral Lysine On Ti-O Surface And Nvestigation On Its Generation Of Nitric Oxide

The living body has a typical chiral character,and amino acids,carbohydrates,phospholipids of the body have a specific chiral configuration.Studies have shown that when the surface of biological material has a specific chirality,the life system will recognise the chirality.Nitric oxide(NO)molecules are produced by healthy endothelial cells,can relax blood vessels,inhibit platelet aggregation and activation.NO has become a hot topic in the field of cardiovascular material research because of its excellent anticoagulant properties.In this paper,Chiral surface will be prepared by L/D-lysine moleculess and Selenocystine which can catalyze NO-S-nitrosothiol(RSNO)release NO,to study the effect of surface chirality on the catalytic release of NO function while improving the blood compatibility of the surface of the material.Firstly,Ti-O films on the surface of single-crystal silicon were fabricated by unbalanced magnetron sputtering technique and then poly-dopamine was deposited on the surface of Ti-O films.Then Selenocystine was fixed on the poly-dopamine.Lastly,the chiral L/D-lysine were grafted on surface.X-ray photoelectron spectroscopy(XPS),Electronic scanning electron microscopy(SEM),water contact angle etc.were used to characterize modified material surface.The effect of surface chirality on the adsorption of bovine serum albumin,fibrinogen and collagen was detected by QCM.The effect of surface chirality on the release of NO from bovine serum albumin was detected by chemiluminescence nitric oxide analyzer.The surface chirality on the blood compatibility of the material was studed by platelet adhesion experiments In vitro and fibrinogen degeneration experiments.The results of water contact angle show that there is almost no difference in water contact angle between different chiral lysine samples.The results of XPS showed that the dopamine and selenocystine were successfully fixed,and content of Se was decreased after grafted L-lysine and D-lysine,but the content of Se was not different.SEM was used to observe the morphology of dopamine on Ti-O,and the surface was rough.The surface of granules was formed.The subsequent introduction of selenocystamine and L/D-lysine did not affect the surface morphology.The results of QCM showed that the surface of grafted L-lysine was more favorable for the adsorption of bovine serum albumin,fibrinogen and collagen than D-lysine.The NO release rate of the surface fixed selenocystine was 3.58±0.76×10-10(mol/cm2·min),while after L/D-lysine was grafted,the The NO release rate of L-lysine sample was 2.42±0.14×10-10(mol/cm2·min),and the NO release rate of D-lysine sample was1.21±0.07×10-10(mol/cm2·min).Although the content of Se on different chiral samples was consistent,the rate of nitric oxide release from samples grafted by D-lysine was significantly lower than L-lysine.Bovine serum albumin was added to the donor solution to simulate the real plasma environment.The results showed that the addition of BSA had little effect on the ability of the sample to catalyze the release of NO.Although the amount of fibrin adsorbed on the surface of the L-sample was significantly larger than D-sample,the Fibrinogen degeneration test showed that the amount of denatured fibrinogen exposed on the L-sample surface was significantly less than D-sample.In the subsequent platelet adhesion and activation experiments,Selenocystine and L/D-lysine samples showed better anti-platelet adhesion and activation ability,when there was added NO donor.And L-Lysine samples had the lowest number of platelet adhereations due to the low degree of fibrinogen degeneration and the large rate of catalytic release of nitric oxide.In this paper,the catalytic activity of surface grafting of different chiral lysine was successfully constructed.The results of surface characterization and biology evaluation showed that the L-lysine surface was better for NO release,platelet adhesion.and Fibrinogen degeneration.