Effects of a titanium dioxide thin film for improving the biocompatibility of diamond-like coated coronary stents

Abstract

This study was performed to evaluate the effects of a diamond-like carbon (DLC) layer on the biological properties of a pre-treated titanium dioxide (TiO2) coronary stent surface. TiO2 and DLC were coated onto a cobalt-chromium stent surface in consecutive order using the plasma-enhanced chemical vapor deposition method (TiO2/DLC). To investigate the effect of TiO2, a group treated only with DLC was also prepared as a control. The surface characteristics were investigated by SEM, ESCA, AFM, and contact angle analyses. To estimate the effect of surface modification on biological response, endothelial cell migration was carried out. As a result, cracking of the coating layer on the strut curved portion in the DLC group was restored in the TiO2/DLC group. ESCA result showed that the peaks sp2 and sp3 were slightly shifted and higher in the TiO2/DLC group. The surface roughness average was highly increased in the TiO2/DLC group (Ra; 18.033) compared to the BMS (Ra; 9.258) and DLC groups (Ra; 10.144). By the increment of Ra, the surface property became hydrophilic in the TiO2/DLC group (39.8°±5.88°) compared to the non-treated (72.7°±2.24°) and DLC (78.6°±2.24°) groups. Endothelial cell migration was significantly increased in the TiO2/DLC group (68.9±13.52%) compared to the non-treated (5.4±3.14%) and DLC groups (22.3±8.22%). Therefore, the improvement of surface properties and endothelial cell migration in the TiO2/DLC group could improve the physiological response in the human body.