Mg-Ti: A Possible Biodegradable, Biocompatible, Mechanically Matched Material for Temporary Implants
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Mg-Ti: A Possible Biodegradable, Biocompatible, Mechanically Matched Material for Temporary Implants Ilona Hoffmann1*, Yang-Tse Cheng1, David A. Puleo2, Guangling Song³, Richard A. Waldo³ 1
Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, U.S.A. Center for Biomedical Engineering, University of Kentucky, Lexington, KY40506, U.S.A. 3 Chemical Sciences and Materials Systems Laboratory, General Motors Global Research and Development Center, Warren, MI 48098, U.S.A. 2
* [email protected] ABSTRACT In recent years there has been a renewed interest in magnesium alloys for applications as temporary biomedical implants because magnesium is both biocompatible and biodegradable. However, the rapid corrosion rate of magnesium in physiological environments has prevented its successful use for temporary implants. Since alloying is one of the routes to slow down corrosion, we report in this publication our investigation of Mg-Ti alloys fabricated by highenergy ball milling as possible materials for biocompatible and biodegradable implants. Titanium was chosen mainly because of its proven biocompatibility and corrosion resistance. Corrosion tests carried out by immersing the Mg-Ti alloys in Hank’s Solution at 37°C showed significantly improved corrosion resistance of the alloy in comparison to pure magnesium. Thus, Mg-Ti alloys are promising new biodegradable and biocompatible materials for temporary implants. INTRODUCTION Materials that can be gradually dissolved and then excreted by the human body may be used as temporary implants [1,2]. The main advantage of such biodegradable implants is that they do not require a second surgery to remove the implant after the healing process is complete [2,3]. Furthermore, the biodegradable implants must also be biocompatible to avoid inflammatory response by the body. Because magnesium is essential to the human body (an adult’s body contains about 1 mole of magnesium [4]) and is naturally found in bone tissues [5], it is non-toxic and but rather beneficial to bone strength and growth [6]. Magnesium is an attractive material for temporary implants because it is both biocompatible and biodegradable. However, the corrosion rate of magnesium in the body is too fast to serve as a suitable temporary implant material. Because the corrosion behavior of magnesium strongly depends on the alloying elements [3], one approach to adjust the degradation rate is alloying. Although many corrosion resistant magnesium alloys have been developed for structural applications, some of them cannot be used in the human body because their alloying elements are detrimental to health [2]. However, since titanium is known to have excellent biocompatibility and corrosion resistance, this work focuses on alloying the fast-corroding magnesium with the corrosion resistant titanium to retard the alloy’s corrosion rate in comparison to pure magnesium. Currently used implant materials, such as titanium and steels, have much higher Young’s modulus values than bone (E = 3 to 20 GPa), resultin
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