Hemocompatibility of diamondlike carbon-metal composite thin films

We have investigated the hemocompatibility of diamondlike carbon-silver composite and diamondlike carbon-titanium composite thin films prepared using a multicomponent target pulsed laser deposition process. These materials were examined using transmission electron microscopy, Raman spectroscopy, nanoindentation, electrochemical charge transfer testing, and platelet adhesion testing. Cross-sectional transmission electron microscopy revealed that silver self-assembles into nanoparticle arrays within the diamondlike carbon matrix in the diamondlike carbon-silver composite film. On the other hand, titanium self-assembles into alternating nanometer-thick titanium carbide layers within the diamondlike carbon matrix in the diamondlike carbon-titanium composite film. The hemocompatibility of these materials was examined using electrochemical charge transfer testing and platelet adhesion testing. A few small, widely scattered crystals were observed on the surface of the unalloyed diamondlike carbon film exposed to platelet rich plasma. On the other hand, dense fibrin networks with densely aggregated platelets were observed on the surfaces of diamondlike carbon-silver and diamondlike carbon-titanium composite thin films exposed to platelet rich plasma. Electrochemical testing revealed that the time constant for the diamondlike carbon thin film (lambda=1) was significantly higher than those for the diamondlike carbon-silver and diamondlike carbon-titanium composite thin films. These results suggest possible uses for diamondlike carbon thin films and diamondlike carbon-metal composite thin films as coatings in next generation cardiovascular implants. (c) 2006 Elsevier B.V. All rights reserved.