Study On Deformation Behaviors Of Titanium Surface Modification With Heparin-Albumin Multilayers Using Electrostatic Layer-By-Layer Self-Assebly Technique

The heparin (Hep) and albumin (Alb) were assembled onto the ultrar thin high purity titanium surface by a layer-by-layer (LBL) self-assembly technique. The positively charged poly-L-lysine (PLL) layer was firstly absorbed onto the titanium surfaces that treated by alkali activation. Then the biofunctional multilayer was constructed by alternating deposition of negatively charged heparin and positively charged albumin via electrostatic interactions. Lastly the samples were bended by outside force with different curvature. The chemical composition of sample surfaces was investigated by Fourier transform infrared spectroscopy (FTIR). The change of surface hydrophilicity and energy during assembly process were investigated by contact angle measurement. The surface topography was investigated by color three-dimensional laser scanning confocal microscope and scanning electron microscope (SEM). The blood compatility was evaluated by in vitro platelet adhesion test. In total, the aim of this study was to find out the influence of outside force on the physical and chemical characteristic, as well as the blood compatility of LBL multilayer assembled surface.The FTIR result showed that the heparin and albumin had been successfully assembled onto the titanium surface. The conclusion was further confirmed by water contact angle measurement. With the increasement of layers, the water contact angle was higher, which indicate that the number of constructed layer should be at a suitable range, but not the more the better.The result of confocal laser scanning microscope showed that the sample appeared crack when the sample was bended.The result of scanning electron microscope showed that with the increasement of layers, the surface was smoother. The samples clear crack when the bending diameter reached5mm. Meanwhile, the surface with more assembled layers, exhibit much more and larger crack.In vitro platelet adhesion test showed that the adhesive blood platelets were increased when the sample was bended, especially in the samples with the bending diameter of 15mm and10mm. Under different bending diameters, platelet aggregation percentage increased after bending. On the surface of17layers, adhesive blood platelets were the fewest one.As stated previously, titanium surface was modified with heparin-albumin multilayers using electrostatic layer-by-layer self-assebly technique.when outside force made it bending, the surface properties may chang, and subsequently affected the blood compatility of the matierals.