鎂金屬材料近年來被認為是一種新的可降解金屬植體，植入後可於一段時間後被人體所吸收，降解成分可刺激骨細胞活性，適合應用在短期植入的人工植體上，有機會取代目前臨床使用之不銹鋼與鈦金屬，可被視為第三代生醫材料。但由於抗腐蝕性差，實驗顯示鎂材料自體降解速度過快，過多的腐蝕產物將影響骨整合，損失患部早期的恢復功能，可能引起身體異常反應。然而，其作為植入材料有以上弱點外，該材料還提供了其它金屬所沒有的優點，如重量輕及更近似於天然骨的力學性質，因而減少了應力遮蔽效應，因此提高材料表面的耐蝕性將可大幅提高其應用性。
本實驗中所使用的原料是純鎂基材（純鎂，不存在雜質於表面）和經過表面磨砂（氧化鋁顆粒殘留於表面，模擬表面嚴重合金化）之兩種情況。兩種試樣的表面將會經過氟基轉化改質，再使用以溶膠-凝膠法製備而成的氫氧基磷灰石(HA)及鋅參雜之氫氧基磷灰石(Zn-HA)塗覆於表面，作為生物功能性外層，以此誘導鎂金屬植入物的表面有更好的骨再生。本研究並採用電化學測試，浸泡試驗，細胞毒性及血液相容性檢測對所有樣本進行分析。
研究結果表明，溶膠-凝膠法所製備的磷酸鈣膠體於400oC時可以相轉化為氫氧基磷灰石。然而，提高煅燒溫度或參雜適量的鋅元素，可以改善氫氧機磷灰石之結晶性、分散性以及塗層貼附能力。並於5%鋅摻雜的樣品中成功去除殘留的TCP相，產生新的鋅取代磷灰石（Ca10Zn0.12（PO4）6（O0.24（OH）1.76）相，並且經高溫煅燒後於介面處發現氟離子擴散誘導界面轉化成氟基磷灰石(FA)的現象。於體外腐蝕試驗中，經過電化學測試、浸泡測試及離子層析分析後，說明在500oC的煅燒溫度及5%鋅的參雜可以有效改善腐蝕特性。細胞相容性及血液相容性的研究中亦顯示表面塗有氫氧基磷灰石或鋅參雜之氫氧基磷灰石皆有提升細胞存活率及降低溶血率的能力，並以含鋅組別之效果最為明顯，輔以腐蝕試驗的結果，說明鋅參雜之氫氧基磷灰石塗層具有相當好的骨科植體表面適用性，可改善可降解鎂金屬之應用限制，為一種新式且有效的生醫鎂材表面處理技術。

As a biodegradable implant, magnesium faces an obstacle that is the corrosion rate too fast. As a result, magnesium implant disintegrates earlier than wound healing of the tissue around implantation site, high corrosion product altered osseointegration, which lost its restoration function, especially in orthopedic application, before the tissue completely healing and get the tissue’s original function restored, and high concentration of magnesium ions released from the implant inhibited the crystalline bone growth around the implant. However, offers some advantages that are not available from other metals such as light in weight resemble to natural bone and Young’s modulus closer to natural bone, reducing the stress shielding.Hydroxyapatite which mimics the composition of the natural bone can be fabricated by chemical formula. Zinc as a trace element in human bone reported plays role in biological function that induce osteoblast growth during wound healing in the bone formation process. This study is to investigate the corrosion and compatibility of pure magnesium coated with zinc-doped hydroxyapatite.
In this experimentthe pure magnesium specimens were either inflat surface or sandblast surface. Then both types of specimens were applied surface conversion coating using hydrofluoric acid)as treated specimens), and then coated with zinc (5 wt%)-doped calcium phosphate and pure calcium phosphate, prepared based on sol-gel method. All specimens were analyzed using electrochemical tests, immersion tests, and cytotoxicity assay.
Calcium phosphate was transformed to hydroxyapatite started from 400oC of calcination and the crystallinity of hydroxyapatite was higher in 500oC. Zinc-doped calcium phosphate could successfully disappeared degradable tricalcium phosphate phase, producing zinc substitute hydroxyapatite (Ca10Zn0.12 (PO4)6(O0.24(OH)1.76) phase, calcium zinc phosphate phase, and also fluoroapatite formation during calcination by diffusion from interface layer (MgF2).
The hydrofluoric acid treated specimen groups improved the corrosion rate of magnesium compared to untreated groups which treated groups preferred pitting corrosion attack while untreated groups occurred corrosion on the whole surface. Meanwhile, zinc-doped calcium phosphate showed better performance as a coating layer on magnesium compared with pure calcium phosphate coating. Zinc caused loss agglomeration of calcium phosphate powder and was able to coat on magnesium specimen denser than pure calcium phosphate coating. Therefore, magnesium substrates coated with zinc-doped calcium phosphate resulted in increasing corrosion protection according electrochemical and immersion tests. Moreover, the cytocompatibility tests, viability and hemolysis assay, showed that surface conversion, the zinc-doped and pure calcium phosphate coating on substrate increased cell viability of MG63 cells and reduced hemolysis in rabbit blood.
In conclusion, fluoride conversion and zinc (5 wt%) -doped calcium phosphate on both pure magnesium and alumina sandblast magnesium can improve their corrosion properties, and enhance cytocompatibility, especially for zinc-doped hydroxyapatite.

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