Enhancing hemocompatibility of titanium alloys through plasma immersion ion implantation

Titanium and its alloys have been extensively used in biomedical applications due to their recognized biocompatibility in contact with bone, mechanical strength, and corrosion resistance. However, their use in blood-contacting medical devices, such as coronary stents and valves, is limited, regarding thrombus formation and restenosis. Surface modification has the potential to enhance blood-implant interaction. This study investigates the effects of oxygen plasma immersion ion implantation on the surface properties of pure titanium, Ti6Al4V, and Ti–15Mo alloys, with treatments conducted at two bias voltages (Ubias = −1 kV and −10 kV). Bias voltage was hypothesized to influence surface chemistry, topography, roughness and physical properties, which are key factors in blood protein adsorption and the coagulation cascade. Physicochemical properties were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurements, high-resolution X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Hemocompatibility was assessed through hemolysis and clotting time tests. Results demonstrated that blood clotting was significantly delayed within the first 15 min of blood contact for all the treated surfaces, with no hemolytic reactions observed. Among the tested samples, Ti6Al4V modified at a lower bias voltage exhibited the most promising results, forming a smooth, hydrophilic surface with an oxide layer that enhanced hemocompatibility compared to other substrates. These findings reveal the potential of this plasma treatment to optimize the hemocompatibility of titanium alloys, providing a promising pathway for improving the performance of blood-contacting medical devices.