화학공학소재연구정보센터
Applied Surface Science, Vol.463, 732-740, 2019
Hemocompatibility and adhesion of heparin/dopamine and heparin/collagen self-assembly multilayers coated on a titanium substrate
Heparin/dopamine and heparin/collagen multilayers were prepared by using self-assembly technique in this work. The 4 and 9 multilayers were built by 30-min rinse in each solution for coating the surfaces of commercial pure titanium (cp-Ti) substrates to increase the substrates' hemocompatibility. All cp-Ti substrates were electropolished and pretreated in a dopamine solution in advance. For samples with 4 heparin/dopamine multilayers, an extended 60-min treatment was used to investigate the effect of coating time. We compared the adhesion and wear resistance of these two types of multilayers after the completion of treatment. The hydrophilicity was tested by the water contact angle, and the surface morphologies were investigated by scanning electron microscopy. The thickness was observed under a focused ion-beam microscope. The adhesion of the as-built multilayers was studied with nano-scratch tests. The amount of heparin that attached to the samples was measured by toluidine blue O (TBO) test. The blood compatibility was verified by hemolysis ratio, platelet coverage area, and activated partial thromboplastin time (APTT) in vitro. In addition, the adhesion strength of multilayers in an orbital shaking test (OST), i.e. a simulated blood shear flow test under various durations, was assessed by the measurement of APTT and TBO tests. The results show that the thicknesses of both multilayers with the same coating number were nearly the same and that of heparin/dopamine one increased with the extended coating time as well. However, the number of heparin/collagen multilayers higher than 4 had trivial contribution to the adhesion strength of the as-built coatings, which was different from that of heparin/dopamine ones. After different time duration of erosive shear flow, the corresponding APTT and TBO tests of OST samples revealed that the anticoagulant performance and the remaining heparin of both multilayers changed in a contrary way. According to the summary, we proposed two tribological mechanisms which is believed helpful to the future studies and applications under the physiological blood-contact fluid.