鎂合金植入醫材由於具備生物降解特性，且生成的物質能被生物體吸收並排出體外，從而避免二次手術取出，能減輕病人的負擔與手術風險。與傳統金屬骨修復材料鈦合金與不鏽鋼相比，鎂合金的基本機械性質與骨組織最為相近，能夠避免應力屏蔽效應。另外，鎂合金具有良好的生物相容性，且其降解的成分能夠誘導新生骨生成，是理想骨修復材料。目前鎂植入材面臨降解速率過快導致產生大量氫氣聚集於植入周圍因而引發發炎。若透過添加合金元素能夠增強鎂合金的機械力學並得到合適的降解速率，故本研究添加鋅、鋯元素來強化其機械性質與緩和降解速度。
為了改善鎂合金的快速降解性，本研究對鎂鋅鋯合金以380℃-2hr鈍化熱處理在表面生成一層氧化膜，並在表面製備一層單元不飽和脂肪酸塗層，以降低降解速率並提高表面的生物相容性。在拉伸試驗中顯示，鈍化熱處理能夠有效提升材料延性。為評估力學性能的衰退速度，進行浸泡實驗後的拉伸試驗，結果顯示材料延性與強度會隨著浸泡時間而逐漸衰減，但鈍化熱處理材料衰減程度低於原材，並能在浸泡四周後仍維持較佳的強度與延性。鈍化熱處理可使得材料內部均質化，並且在表面生成氧化膜以減緩降解速率；而單元不飽和脂肪酸塗層能阻擋鎂合金與溶液產生反應亦能提高抗腐蝕能力。細胞毒性與細胞貼附實驗結果中，單元不飽和脂肪酸塗層在細胞增生的表現為最為優秀，而鈍化熱處理稍差，但兩者皆具有良好的生物相容性。此外，在細胞貼附實驗中，單元不飽和脂肪酸塗層在初期貼附中細胞很快就有觸手生成，說明塗層亦對於促進細胞貼附具有優勢。
最終，進行體內測試-蘭嶼豬動物實驗，將鎂鋅鋯合金透過擠型並切削成中空埋頭式雙螺紋骨釘，再進行380℃-2hr鈍化熱處理後，植入蘭嶼豬左前肢。植入試驗十六周後，由於鎂合金降解，所以機械性質降低，無法緊實牢固癒合傷口，因此新生骨癒合現象不顯著，但前肢功能性完全，在植入測試四周時，豬隻已能正常行走。
本研究經由表面改質後，可以使鎂鋅鋯合金骨釘不僅有良好的降解性、細胞貼附與細胞增生等性質，亦能減緩力學性質的衰退速度，並在植入生物體後透過降解免於二次手術取出，相關成果具臨床應用潛力。

Due to the biodegradation characteristics of magnesium alloy implanted medical materials, the generated materials can be absorbed by organisms and removed out of the body, so as to avoid the second operation and reduce the burden of patients and surgical risks. Currently, magnesium implants degrade too rapidly, resulting in a buildup of hydrogen around the implants that can cause inflammation. In this study, zinc and zirconium were added to enhance the mechanical properties and ease the degradation rate of magnesium alloys.
In the study, a layer of oxide film was formed on the surface of Mg-Zn-Zr alloy by heat treatment 380℃-2hr, and a layer of monounsaturated fatty acid coating was prepared on the surface to reduce the degradation rate and improve the biocompatibility of the surface. Passivation heat treatment can slow down the degradation rate. The monounsaturated fatty acid coating can prevent magnesium alloy from reacting with solution and improve corrosion resistance. The results of cytotoxicity and cell adhesion showed that the monounsaturated fatty acid coating showed the best performance in cell proliferation. In the cell adhesion experiment, the monounsaturated fatty acid coating was quickly generated by tentacles in the initial adhesion, indicating that the coating also had advantages in promoting cell adhesion.
Finally, in animal experiments, after 16 weeks of magnesium alloy implantation test, although the new bone healing was not significant, the forelimbs were fully functional, and the pigs could walk normally at four weeks of implantation test.

1. Zheng, Y. F., Gu, X. N., and Witte, F. Biodegradable metals. Materials Science and Engineering: R: Reports77 (2014)1-34.
2. Navarro, M.,Michiardi, A., Castano, O., Biomaterials in orthopaedics. Journal of the Royal Society Interface5.27 (2008) 1137-1158.
3. Cao, W., and Hench, L. L Bioactive materials. Ceramics international22.6 (1996) 493-507.
4. Suchanek, W., and Yoshimura, M. Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants. Journal of Materials Research13.1 (1998) 94-117.
5. Hench, L. L., and Polak, J. M. Third-generation biomedical materials. Science295.5557 (2002)1014-1017.
6. E. PayrBeiträge zur Technik der Blutgefäss- und Nervennaht nebst Mittheilungen über die Verwendung eines resorbirbaren Metalles in der Chirurgie Arch Klin Chir, 62 (1900) 67-93
7. Staiger, M.P., Pietak, A. M., Huadmai, J., Its alloys as orthopedic biomaterials: a review Biomaterials, 27 (2006) 1728-1734
8. P.E. DeGarmoMaterials and processes in manufacturing (5th ed), Collin Macmillan, New York (1979)
9. Ilich, J. Z.and Kerstetter, J. E., Nutrition in bone health revisited: A story beyond calcium. Journal of the American College of Nutrition(2000).19(6)715-737.
10. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes.Dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. National Academies Press (US), (1997).
11. J. Vormann, Control of biodegradation of biocompatable magnesium alloys, Corrosion Science,Volume 49,Issue 4, April (2007)1696-1701
12. H. Zreiqat, C.R. Howlett, A. Zannettion, P. Evans, G. Schulze-Tanzil, C. Knabe J. Biomed. Mater. Mechanisms of magnesium-stimulated adhesion of osteoblastic cells to commonly used orthopaedic implants Res., 62 (2002)175
13. Nagels, J., Stokdijk, M., andRozing, P. M."Stress shielding and bone resorption inshoulder arthroplasty."Journal of shoulder and elbow surgery12.1 (2003)35-39.
14. N.E. Saris, E. Mervaala, H. Karppanen, J.A. Khawaja, A. LewenstamMagnesium. An update on physiological, clinical and analytical aspects Clin Chim Acta, (2000)1-26
15. F. Witte, V. Kaese, H. Haferkamp, E. Switzer, A. Meyer-Lindenberg, C.J. Wirth, et al.In vivo corrosion of four magnesium alloys and the associated bone response Biomaterials, (2005)3557-3563
16. A. LambotteL’utilisation du magnesium comme materiel perdu dans l’osteosynthèse Bull Mém Soc Nat Chir, (1932)1325-1334
17. V.V. Troitskii, D.N. TsitrinThe resorbing metallic alloy ‘Osteosinthezit’ as material for fastening broken bone Khirurgiia, (1944) 41-44
18. Avedesian, M. M., and Baker, H.,eds.ASM specialty handbook: magnesium and magnesiumalloys. ASM international, (1999)
19. Mjoberg, B., Hellquist, E., Mallmin, H., W., Evaluation of microstructural effects on corrosion behavior of AZ91D magnesium alloy, Corrosion Science, (2000)42(8) 1433-1455.
20. Zhang,S. X., Zhang, X. N.,Zhao, C. L., Li, J. Song, Y., Xie, C. Y., Tao, H., Research on an Mg-Zn alloys as a degradable biomaterial. Acta Biomaterialia, (2010)6(2) 626-640.
21. Cai,S. H., Lei, T.,Li N.,Effects of Zn on microstructure,mechanical properties and corrosion behavior of Mg-Zn alloys, Materials Science & Engineering C-Materials for Biological Application, (2012) 32(8) 2570-2577
22. Gandel, D. S., Easton, M. A., Gibson, M. A., Abbott, T., and Birbilis, N. "The influence of zirconium additions on the corrosion of magnesium."Corrosion Science81 (2014)27-35
23. Avedesian, M. M., and Baker, H.,eds.ASM specialty handbook: magnesium and magnesiumalloys. ASM international, (1999)
24. Li N, Zheng Y. Novel magnesium alloys developed for biomedical application: a review. J Mater Sci Technol. (2013)29(6)489–502.10.1016/j.jmst.2013.02.005
25. Huan Z.G., Leeflang M.A., In vitro degradation behavior and cytocompatibility of Mg–Zn–Zr alloys. J Mater Sci: Mater Med. (2010)21(9)2623–2635.
26. Sun, M., Wu, G., Wang, W., and Ding, W. "Effect of Zr on the microstructure, mechanical properties and corrosion resistance of Mg–10Gd–3Y magnesium alloy."Materials Science and Engineering: A523.1-2 (2009)145-151.

27. Hirai, K., Somekawa, H., Takigawa, Y., and Higashi, K. "Effects of Ca and Sr addition on mechanical properties of a cast AZ91 magnesium alloy at room and elevated temperature."Materials Science and Engineering: A403.1-2 (2005) 276-280.
28. Zhang, E., and Yang, L. "Microstructure, mechanical properties and bio-corrosion properties of Mg–Zn–Mn–Ca alloy for biomedical application."Materials Science and Engineering: A497.1-2 (2008) 111-118.
29. S. Hiromoto, A. YamamotoControl of degradation rate of bioabsorbable magnesium by anodization and steam treatment Mater Sci Eng C, 30 (2010)1085-1093
30. J. Li, Y. Song, S. Zhang, C. Zhao, F. Zhang, X. Zhang, et al.In vitro responses of human bone marrow stromal cells to a fluoridated hydroxyapatite coated biodegradable MgZn alloy Biomaterials, 31 (2010)5782-5788
31. K. Chiu, M. Wong, F. Cheng, H. ManCharacterization and corrosion studies of fluoride conversion coating on degradable Mg implants Surf Coat Technol, 202 (2007)590-598
32. Terés S, Barceló-Coblijn G, Benet M, Alvarez R, Bressani R, Halver JE, Escribá PV.,Oleic acid content is responsible for the reduction in blood pressure induced by olive oil. Proc Natl Acad Sci U S A. (2008) Sep 16;105(37)13811-6. doi: 10.1073
33. Sales Campos H, Souza PR, Peghini BC, da Silva JS, Cardoso CR.An overview of modulatory effects of oleic acid in health and disease. Mini Rev Med Chem. (2013) Feb;13(2)201-10.
34. Klocke F, Schwade M, Klink A, et al. EDM machining capabilities of magnesium (Mg) alloy WE43 for medical applications. Procedia Eng. (2011)19:190–195.10.1016/j.proeng.2011.11.100
35. Lambotte A: Lutilisation du magnesium comme materiel perdu dans losteosynthese ,The use of magnesium as material for osteosynthesis. Bull Mem Soc Nat Chir 28, (1932)1325–1334
36. McBride ED: Absorbable metal in bone surgery. JAMA 111, (1938) 2464–2467
37. Sanchez AH, Luthringer BJ, Feyerabend F, Willumeit R: Mg and Mg alloys: How comparable are in vitro and in vivo corrosion rates? A review. Acta Biomater 13, (2015) 16–31
38. H. R. Bakhsheshi-Rad, E. Hamzah, M. Medraj, M. H. Idris, A. F. Lotfabadi, M. Daroonparvar and M. A. M. Yajid, Effect of heat treatment on the microstructure and corrosion behaviour of Mg–Zn alloys, Materials and Corrosion (2014) 65, No. 10 DOI: 10.1002/maco.201307492
39. Niinomi, M . "Recent metallic materials for biomedical applications." Metallurgical and materials transactions A 33.3 (2002)477 486
40. A. Rohman & Y.B. Che Man, Application of FTIR Spectroscopy for Monitoring the Stabilities of Selected Vegetable Oils During Thermal Oxidation, International Journal of Food Properties, ISSN: 1094-2912 (Print) 1532-2386
41. Zhao, X.; Shi, L.; Xu, J. Mg-Zn-Y alloys with long-period stacking ordered structure: In vitro assessments of biodegradation behavior. Mater. Sci. Eng. C (2013)33, 3627–3637.
42. Lederer, S.; Lutz, P.; Fürbeth, W. Surface modification of Ti 13Nb 13Zr by plasma electrolytic oxidation. Surf. Coat. Technol.(2018)335, 62–71.
43. Yunchang Xin, KaifuHuo, HuTao, GuoyiTang, Paul K.Chu, Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment, Acta Biomaterialia Volume 4, Issue 6, November (2008)2008-2015
44. Fung, Y.C.Biomechanics: mechanical properties of living tissues. Springer Science & Business Media, (2013).
45. Huan Z.G., Leeflang M.A., Zhou J., Fratila-Apachitei L.E., Duszczyk J. In vitro degradation behavior and cytocompatibility of Mg–Zn–Zr alloys. J. Mater. Sci. Mater. Med. (2010)21:2623–2635.