| 摘要: | 鎂基金屬玻璃因其優異的機械性質、安全的生物相容性及具可降解性，其應用於生醫植入物已受到科學家及臨床上的關注，但其本質上的脆性限制其實際應用。本研究選擇較佳玻璃成形能力的Mg66Zn29Ca5為基礎材料，以外添加金屬顆粒的方式來提升鎂基金屬玻璃的破裂韌性，本研究選擇添加3種具有生物相容性的微米級金屬顆粒，分別為鈦鋯基金屬玻璃顆粒、鐵金屬顆粒及多孔鉬金屬顆粒，其添加量以5到30 Vol.%為實驗參數，其中以多孔鉬顆粒表現最為顯著，在20 Vol.%的多孔鉬添加下，3mm柱狀試片其破裂韌性從基材的1.1 MPa‧m1/2提升到6.01 MPa‧m1/2及機械強度仍維持在672MPa，然而在4 mm的棒狀試片中，明顯的結晶物析出於鎂基金屬玻璃及其複材中，限制了生醫植入物的應用，因此我們設計出以鎂棒為核、金屬玻璃為殼的核殼結構企圖突破金屬玻璃其尺寸上的限制，實驗結果亦顯示核殼結構有效提升外圍金屬玻璃其玻璃形成能力及維持適當的機械強度，在6週相關生醫試驗過後，證明其有效調控降解速率及維持在人體的機械性質，且仍維持良好的生物相容性及幫助骨細胞成長。
對於生醫植入物而言，細胞附著能力是被受關注的議題，表面粗糙度對骨細胞的初始附著及成長有極大的影響，本研究利用3種不同號的砂紙#240、#800、#2000來探討金屬玻璃表面粗糙度對降解能力、MG63骨細胞附著能力及成長能力，研究結果顯示表面粗糙度對鎂基金屬玻璃降解能力沒有顯著的影響，而較粗糙的表面具有較佳的鈣離子堆積能力，在#800號砂紙處理過後的表面具有較佳的MG63細胞附著性及提供較佳的遷移環境
過快的降解性質是鎂合金應用於生醫植入物的重大問題，本研究利用鎂基金屬玻璃鍍於ZK60鎂合金上，以此改善其機械性質及調控其降解能力。鎂基金屬玻璃薄膜成功藉由真空濺鍍法製備於ZK60鎂合金基板上，鎂基金屬薄膜與ZK60基板間具有良好的附著性並有效提升機械性及抗腐蝕能力，在機械性質方面，表面硬度提升至204Hv及抗彎曲能力從216MPa提升至254MPa，在抗腐蝕能力方面，其腐蝕電流從2.88 × 10-5 A/cm2降至1.66 × 10-6 A/cm2。
;Mg-based bulk metallic glass(BMG) and its composites have been investigated for their huge potential for application in orthopedic implants due to their biocompatibility, low degradation rate, and osteogenetic ability. However, the intrinsic brittleness of Mg-Zn-Ca BMG has to be significantly improved for commercial application. Therefore, the concept of ex-situ adding metallic particles is introduced to produce Mg-Zn-Ca bulk metal glass composite (BMGC) to meet the requirement of mechanical properties. In this study, the Mg66Zn29Ca5 BMG was selected as base alloy and added different micro-spherical metal particles (Fe, porous Mo and TiZr-based metallic glass powder) to enhance its fracture toughness. The optima results occur at 3 mm Mg-Zn-Ca BMGC rods with 20vol.% porous Mo particles, the fracture toughness increased up to 6.1 MPa‧m1/2 from 1.1 MPa‧m1/2 of based and remained the compressive strength of 672 MPa. However, 4mm size rods were unstable structures combined with amorphous and crystalline structures due to the insufficient cooling rate. Therefore, we design a core-shell structure comprising a pure Mg crystalline core and amorphous shell in order to overcome the size limit imposed by the cooling rate effects. As a result, the shell of 4mm core-shell Mg BMG rods exhibits fully amorphous shell and have a lower degradation rate after six weeks of degradation. Moreover, the biocompatibility and osteogenic effects were similar between the core–shell and solid structures of Mg-based BMG. In conclusion, the core–shell structure of Mg-based BMG exhibits suitable mechanical properties and lower degradation rate while still enhancing osteogenic potential in vitro.
As an orthopedic implant, initial cell adhesion was a critical issue for subsequent osteogenesis and bone formation because the first contact between cells and the implant occurs upon the implants surface. Three different surface roughness of Mg-based BMG samples were designed to understand the degradation behavior of Mg-based BMG and the adhesion ability and osteogenetic ability of the contact cells. The surface roughness could not affect the degradation behavior of Mg66Zn29Ca5 BMG. The surface polished via #800 grade sandpaper possessed well-attached surface and a good cell viability environment for MG63 osteoblast-like cells. Moreover, higher surface roughness was investigated more calcium and mineral deposition which verify the relationship between surface roughness and cell performance.
The Mg-Zn-Ca metallic glass thin film (MGTF) was coated on the surface of ZK60 substrate improve its mechanical properties, corrosion resistance and biocompatibility. Through the DC vacuum sputtering machine, the Mg-based metallic glass coating was successfully coated on the ZK60 substrate, and the structure of the Mg-based metallic glass coating remained amorphous. The results of coating adhesion test show that the Mg-based metallic glass coating possess high adhesion property with 5B grade of tape testing (0% of the film peels off from the substrate). Meanwhile, the hardness of the Mg-based metallic glass coating can reach to 240 Hv by nano-indentation. Through the three-point bending testing, the Mg-based metallic glass thin film MGTF coating with 1000 nm thickness can effectively improve the bending strength about from 216 MPa to 254 MPa. In addition, the results of electrochemical corrosion test present that the Mg-based metallic glass MGTF coating prepared by 30W sputtering possessed the best corrosion resistance. The corrosion current in 30W power was 1.66 × 10-6 A/cm2, which is much lower than the ZK60 alloy (2.88 × 10-5 A/cm2). |
