理學院: 化學研究所指導教授: 陳振中楊昇祐Yang, Sheng-YuSheng-YuYang2017-03-022018-07-102017-03-022018-07-102016http://ntur.lib.ntu.edu.tw//handle/246246/271953非晶態碳酸鈣一般被視為是所有結晶碳酸鈣的重要前驅物。近年來雖然有許多的研究著重於探討非晶態碳酸鈣的結構，但對於其是否有短程有序的排列等說法仍無法被證實，Colfen團隊在2008年觀察到在pH 8.75與pH 9.80兩個條件下製備的ACC呈現不同的溶解度，因而定調為不同類型的ACC，而這樣的說法更在2010年透過固態核磁共振儀獲得進一步的佐證。 在水中生物體內的ACC往往含有大量的鎂例如海膽，而依據品種與生長階段的不同，鎂含量可從5%到45%。鎂離子的進入將可以抑制結晶現象的發生因而大大的提升ACC的穩定度，此外，除了鎂離子會對ACC的性質產生影響之外，在pH 8到pH 9的溶液中，大量的碳酸氫根離子與其他陽離子例如鈣離子、鎂離子的鍵結行為也會對Mg-ACC的結構環境與成核機制產生劇烈的影響。 在本論文中，我們將沿用上個研究工作所建立的微量混合法，合成不同pH條件的Mg-ACC，並進一步針對其化學組成與鎂鈣空間分布關係進行探測，此外，我們也嘗試建構一個熱力學模型來模擬Mg-ACC的形成機制。從NMR的光譜中，我們可以觀察到Mg-ACC確實由ACC與AMC兩個可被清楚分別的特徵峰所組成，此外，透過13C同核相關實驗的測量可以斷定兩者以均勻混合的方式存在同一個結構基質當中，而在熱力學模型模擬的實驗中，我們以含鎂量、碳酸根含量、碳酸氫根含量三個指標來斷定模型與真實系統的相似性，結果顯示兩者有良好的符合度，說明此模型存在一定程度的真實性，因此我們也許可以進一步透過此模型去推測Mg-ACC可能的形成機制。Amorphous calcium carbonate (ACC) is commonly regarded as a precursor of all well-crystallized calcium carbonate. In recent years, many investigations have focused on probing the structural ordering of ACC. However, it remains unclear whether this amorphous precursor has an explicit short-range structure. According to Colfen and Gebauer (2008), ACC precipitated from solutions at pH 8.75 and pH 9.80 have distinctive values of solubility product. Consequently, the concept that ACC can exhibit different structural types has been developed and partially corroborated by the 13C magic-angle spinning NMR in 2010. In marine organisms such as sea urchin, ACC usually contains substantial amount of magnesium content, ranging from 5 to 45%. The exact amount of Mg depends on the growth state and phyla of the species. The presence of magnesium in ACC (Mg-ACC) would inhibit the crystallization of calcium carbonate and hence would greatly increase the stability of Mg-ACC. In a solution of carbonate salt at pH 8 to 9, most of the carbonate ions are protonated. Thus, the binding behavior of bicarbonate ions and other cations such as Ca2+ or Mg2+ could have substantial effect on the formation of Mg-ACC. Nonetheless, relatively few studies have been carried out to investigate this effect. Previously, our laboratory successfully developed a method based on micromixing to prepare Mg-ACC with good reproducibility in Mg/Ca ratio. In this thesis, we predominantly focused on investigating the chemical composition and the homogeneity of Mg-ACC prepared from the mother liquid with different pH conditions. To further unravel the formation mechanism of Mg-ACC, we constructed a model based on the thermodynamic equilibrium. The Solid-state NMR data revealed that there are two types of carbonate ions in Mg stabilized amorphous calcium carbonate (ACC), whose short-range orders were identical to those of ACC and amorphous magnesium carbonate (AMC). 13C homonuclear correlation spectroscopy supported that Mg-ACC comprised a homogeneous mixture of the nano-clusters of ACC and AMC. Besides, the good agreement between the simulated results and the experimental data signified that the model constructed in this work is highly analogous with the real situations. Therefore, we could legitimately assume that the formation of Mg-ACC occurred through the process of informing the prunucleation cluster.5826152 bytesapplication/pdf論文公開時間: 2017/2/15論文使用權限: 同意有償授權(權利金給回饋學校)生物礦化非晶相碳酸鈣固態核磁共振儀Biomineralizationamorphous calcium carbonateNMR[SDGs]SDG14thesis10.6342/NTU201601787http://ntur.lib.ntu.edu.tw/bitstream/246246/271953/1/ntu-105-R02223174-1.pdf