Study On Preparation Of Aligned Carbon Nanotubes And Its Primary Application Of Blood Compatibility

Blood compatibility is one of the most important factors for biomaterials applied in blood-contacting environment.The research on blood compatibility of biomaterials developed rapidly.However,they can't meet demands of materials for in vivo medical applications.In recent years,the investigation of carbonaceous materials on blood compatibility have attract people's wide attention,such as artificial blood vessel, artificial heart valve,worn surface of artificial joints and blood purification.As a new kind of carbonaceous material,carbon nanotubes take on excellent mechanical, electrical,magnetic and thermal properties.In consequence of their unique structures and chemical constituents,the interaction between them and blood may be different from traditional materials.Nickel films with different parameters were prepared by K575X magnetron sputtering coater using magnetron sputtering method.Then the nickel films were etched at high temperatures to obtain different kinds of structures.The influences of the etching time,temperature and thickness of nickel films on the results of pretreatment was investigated.Finally,we grasped the preliminary rule of ammonia etching.The functional mechanism of ammonia was also analyzed.Nickel films which were deposited on silicon wafers were chosen as substrates to prepare carbon nanotubes with various morphologies via chemical vapor deposition. Scanning electron microscope,transmission electron microscope,Raman spectroscopy and energy dispersive x-ray spectrometer were employed to characterize the aligned carbon nanotubes.The effects of temperature,growth time,gas flow,thickness of the catalytic film were investigated.There existed an optimum range among these factors. Growth mechanism of aligned carbon nanotubes were discussed on the basis of the experimental results.The measurement of contact angles on these surfaces were employed to study the influence of technological parameters on their surface characteristics.The polar force, dispersive force,ratio of dispersive component to polar component,surface tension, adhesive work,interfacial tension were calculated according to contact angles obtained.Blood compatibility test for carbon nanotubes films in vitro was performed to evaluate their blood compatibility,including platelet adhesion test,dynamic clotting time test and haemolysis experiment.The micro-nano structure of carbon nanotubes is closely related to its blood compatibility.It reveals low surface tension,adhesive work and ratio of dispersive component to polar component,high interfacial tension are favorable for the decrease in the amount of adherent platelet and out of shape on the sample.Carbon-nanotube surface with high contact angles could prolong the dynamic clotting time.Hemolytic rate of carbon nanotubes films with various structures is lower than 5%,which conforms to the need of biomaterials.