Plasma surface treatment of artificial orthopedic and cardiovascular biomaterials

Plasma surface modification has become a popular method to modify the surface structure and biological properties of biomaterials. By modifying selective surface mechanical and biological properties, conventional materials can be redesigned with their favorable bulk attributes retained. Plasma surface modification can enhance the multi-functionality, mechanical properties, as well as biocompatibility of artificial biomaterials and medical implants. Here, our recent research work on plasma modification of orthopedic materials including titanium and nickel–titanium shape memory alloys as well as diamond-like carbon as cardiovascular materials is described. NiTi alloys that possess shape memory and super-elastic properties are of interest in spinal deformity correction. Shape recovery inside the human body allows for less traumatic gradual correction while obviating the needs for multiple surgeries. However, leaching of harmful nickel ions from the materials causes health hazards and plasma implantation is an excellent means to create a graded barrier layer to impede Ni out-diffusion and improve the corrosion resistance. Our latest results demonstrate that the shape recovery property is not compromised with the plasma treatment. Also described are our results on titanium implanted with calcium and sodium for enhancement of the surface biological properties. With regard to cardiovascular materials, the two main requirements are good surface mechanical properties and blood compatibility. Diamond-like carbon (DLC) is a potential material in artificial heart valve and our recent studies suggest that doping DLC with biological friendly elements such as nitrogen and phosphorus can improve the blood compatibility of the materials.