Improved Mechanical Compatibility and Cytocompatibility of Ta/Ti Double-Layered Composite Coating
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Improved Mechanical Compatibility and Cytocompatibility of Ta/Ti Double-Layered Composite Coating Ding Ding1,2 • Youtao Xie1 • Kai Li1 • Liping Huang1 • Xuebin Zheng1
Submitted: 20 March 2017 / in revised form: 26 June 2017 / Published online: 17 July 2017 Ó ASM International 2017
Abstract In order to improve the mechanical compatibility and cytocompatibility of titanium implants, a composite coating with double layers composed of tantalum and titanium was designed and prepared using plasma spraying technology. In the composite coating, the upper tantalum layer provides a good biocompatibility, and the sublayer of titanium with a porous structure ensures the low elastic modulus. Results show that the fabricated composite coating exhibits a relatively low elastic modulus of 26.7 GPa, which is close to the elastic modulus of human cortical bone. In vitro cytocompatibility evaluation of the composite coating shows that the human bone marrow stromal cells exhibit enhanced adhesion and spreading performance on the double-layered composite coating in comparison with the single-layered titanium coating. In order to eliminate the misgivings of chemical stability of the composite coating in clinical application, electrochemical corrosion of the coating was examined. The results obtained revealed a very weak galvanic corrosion between the tantalum and titanium in the composite coating, which would ensure the safety of the coating in vivo. Keywords cytocompatibility low elastic modulus plasma spraying tantalum coating titanium implant
& Xuebin Zheng [email protected] 1
Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, People’s Republic of China
2
University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, People’s Republic of China
123
Introduction Repair of bone defects resulting from trauma or disease remains a severe barrier for orthopedics. Titanium and its alloy have been widely used for this clinical application under load-bearing condition owing to their superior mechanical properties and chemical stability compared to stainless steel and cobalt-based alloys (Ref 1-3). However, the bulk titanium alloys are bioinert and have significantly higher elastic modulus (120 GPa) than that of natural cortical bone (10 to 30 GPa) (Ref 4). The mismatch between implant and host bone can lead the nearby bone to be insufficiently loaded and become stress shielded, which hinders the bone remodeling and affects healing process (Ref 5). Furthermore, titanium implants cannot bond to bone directly, resulting in excessive micromovement at the bone-implant interface, which is another reason for the loosening of implant. To solve these existing problems, there is a significant demand for carrying out surface modification to enhance the osteogenesis capacity for the titanium implants. Porous materials as orthopedic implants are increasingly attracting the interest of researchers to reduce stiffness mism
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