探討β-三鈣磷酸鹽與硫酸鈣複合材料之性質與降解行為

Abstract

在本研究中，我們透過固態反應法合成β-三鈣磷酸鹽(β-TCP)，並將合成的粉末與半水硫酸鈣(CSH)以不同之重量比例混合、壓錠成生胚。接著透過在高溫下的燒結使生胚緻密化，同時半水硫酸鈣也會轉換為無水硫酸鈣(CSA)。而在本實驗中，我們將會透過檢測相對密度、抗折強度、體外降解行為以及細胞毒性來評估β-TCP/ CSA複合系統作為人工骨替代材之可行性。 結果顯示，透過我們所設計的流程，可以得到高緻密度的β-TCP (96.3%)，且此時的雙軸向抗折強度可達226MPa。而在加入硫酸鈣之後，儘管相對密度仍然能夠維持在90%之上，但即使僅添加了20個重量百分比的硫酸鈣，雙軸向抗折強度卻會大幅下降至62MPa。至於體外降解行為方面，β-TCP的降解速率很慢，而CSA的重量損失則是隨著時間具有上升的趨勢。此外，複合材料的降解行為則主要發生於實驗的初期階段，並且在四至五天後達到飽和，同時伴隨著片狀的微觀結構在表面生成。在細胞毒性的測試中，β-TCP、CSA以及兩者的複合材料都顯示為不具細胞毒性。因此整體而言，將β-TCP與CSA複合是能夠達到調整材料的降解行為，並且也驗證了此複合材料系統作為人工骨替代材之可行性。

In the present study, a β-tricalcium phosphate (TCP) powder has been synthesized through a solid-state reaction at elevated temperature. The powder is then mixed with calcium sulfate hemihydrate (CSH) in various weight ratios, and pressed into green compacts. Densification of the green compacts is conducted by sintering at elevated temperatures, in order to obtain dense bulks with desired compositions. The CSH has transformed into calcium sulfate anhydrate (CSA) during the heat treatment. The relative density, flexural strength, in vitro degradation behavior and cytotoxicity of the composite materials had been examined in order to evaluate the compatibility of the β-TCP/CSA system as synthetic bone graft substitute. The results showed that for TCP samples, a high relative density (96.3%) was achieved after sintering, along with a high flexural strength (226 MPa). Although the composite materials with CSA maintained high relative densities (>90%), the flexural strength had been reduced to a great extent (62 MPa) even when the addition is as low as only 20wt%. As for the degradation behavior, the degradation of β-TCP in simulated body fluid is slow while the accumulated weight loss of pure CSA samples increases with time. On the other hand, the composite samples degraded only at the early stage and saturated after 4 to 5 days, with the formation of plate-like structures on the surfaces. For cytotoxicity test, the β-TCP and its composite with CSA show low toxicity. In summary, the combination of β-TCP and CSA is able to modify the degradation behavior. The present study has demonstrated that the potential of using β-TCP/CSA composites as synthetic bone graft substitutes is high.