Thrombogenesis is the principal problem associated with blood-contacting biomedical devices. One of the important reasons is that most of the materials used in these devices cannot avoid inducing platelet adhesion and activation. Our recent investigation suggested that Ti-O thin film could be an alternative antithrombotic material. In this work, we focus our attention on behavior of platelets adhered on Ti-O film. Platelet adhesion experiments were conducted to examine the platelets/material interaction in vitro and the effect of protein adsorption on platelet adhesion and activation. The specific resultants of platelet release (GMP140) were tested for evaluating the platelet activation. In vivo implantation was used to investigate formation of thrombus. The excellent anticoagulation performance of Ti-O films has been shown in in vivo long-term mplantation. The release of specific resultants GMP140 from platelets contacting to Ti-O film was the lower than LTI-carbon. The morphology of adherent platelets maintainsround and isolated. Apparently, the activation of platelets adhered on Ti-O film was suppressed. The results of in vitro test also suggest that the suppression of platelet activation is related to plasma protein adsorption. Preadsorbing fibrinogen doesn't cause the exacerbation of platelet activation. It seems reasonable to suggest that its excellent anticoagulation is caused by inhibition of adherent platelet activation produced by Ti-O film.

Nitrogen incorporated carbon films were synthesized using plasma immersion ion implantation and deposition at room temperature. Nitrogen partial pressure was varied from 1.0

Surface modification has become a important field in biomaterials research because of the low cost, the high efficacy and the versatility. In this paper some recent applications of surface modification technology on the materials for cardiovascular devices were provided. Three ategories of the surface modification process, biological molecular immobilization, chemical medium binding and energy carrier substances coating or modification are discussed, the authors series work on the surface modification of artificial heart valve and vascular stents etc. are presented. The further development of the field is also discussed.

TiN and Ti-O/TiN films have been deposited on Ti-6Al-4V substrate using plasma immersion ion implantation and deposition (PIII&D). It has been proved that TiN and Ti-O/TiN films both enhance the corrosion resistance of substrate materials. Potentiodynamic polarization curves show that both Ti-6Al-4V substrates deposited with these two kinds of films have lower dissolution urrents than that of the uncoated one. Electrochemical impedance spectroscopy (EIS) measurements indicates that TiN films with high corrosion resistance is mainly due to its barrier-type dense film layer, and that Ti-O/TiN film provides high corrosion resistance is mainly owing to its high corrosion potential (Ecorr). Friction coefficient curves obtained from pin-on-disk wear tests, as well as following SEM observation of wear residual trace width and morphology, indicate that TiN and Ti-O/TiN films both present high wear resistance in comparison with uncoated Ti-6Al-4V.

In the present paper, the scientific basis, technique approaches, the present status and the development trends of surface modification for blood contacting materials are discussed briefly. The work in authors' Lab. is also presented.