Time course analysis of antithrombogenic properties of fluorinated diamond-like carbon coating determined via accelerated aging tests: Quality control for medical device commercialization

We have previously reported that fluorine-incorporated amorphous carbon (a-C:H:F) coating dramatically reduced the number and activation of adherent platelets in contact with human blood. In order to convert a-C:H:F coating into a commercial reality, it is necessary to estimate its life span and the sustainability of antithrombogenic properties using accelerated aging tests under various temperature conditions. The purpose of this study was to investigate the effect of different temperature conditions using accelerated aging tests on the antithrombogenic properties of a-C:H:F. The a-C:H:F film was deposited on silicon substrates from a mixture of acetylene and octafluoropropane using the inductively coupled plasma enhanced chemical vapor deposition method. The a-C:H:F coated substrates were then stored at room temperature, 55 °C, 70 °C and 90 °C, respectively. The surface chemical compositions of a-C:H:F film were examined using X-ray photoelectron spectroscopy (XPS). The antithrombogenic properties were evaluated through incubation with platelet-rich plasma isolated from human whole blood, and the properties of adhesion between film and metallic stents were evaluated by examining before-and-after balloon expansion. The XPS analysis showed that the relative amount of fluorine atoms slightly decreased and the amount of oxygen increased over time on the surface of a-C:H:F samples. Furthermore, the change in chemical composition was the most prominent in the samples stored at 90 °C. However, no significant difference in the number of adherent platelets were observed among a-C:H:F coated sample surfaces after accelerated aging tests, suggesting that changes in chemical composition due to elapsed time and temperature changes do not significantly affect the antithrombogenic properties. Furthermore, the stability of the adhesive properties on a-C:H:F coated stents was revealed, because there were no cracks or instances of delamination on any a-C:H:F coated stent surfaces after expansion. This work demonstrated that excellent antithrombogenic properties of a-C:H:F were maintained over time at each temperature, and thus a-C:H:F film could be utilized as a coating material for medical device commercialization. Prime novelty statement We report that the antithrombogenic and adhesive properties of fluorine-incorporated amorphous carbon (a-C:H:F) are stable even after accelerated aging tests, and thus a-C:H:F film could be utilized as a coating material for medical device commercialization.