以微脂體調控磷酸鈣礦化之研究

Abstract

磷酸鈣是脊椎動物硬組織的主要礦物成分，其在生物體內的礦化過程通常在限制空間中，像是細胞、囊泡或是細胞間介質當中。在本論文中將研究在微脂體內部生成的磷酸鈣礦物的成礦過程。首先我們建立出微脂體-磷酸鈣系統，接著進一步以各種技術鑑定產物。樣品TEM顯示合成的磷酸鈣尺度約50 nm且型貌為團聚狀。由XRD以及FT-IR可發現所合成的樣品具有HAp結晶相，隨著實驗礦化時間的增加，其結晶性會越好。以固態核磁共振技術，我們可以鑑定出樣品中同時含有ACP以及HAp，並且樣品中HAp與ACP在空間上排列相當緊密，會呈現類似「固態分散體」的模型。由此可建立成礦的過程：均勻分佈在ACP團簇當中的HAp晶粒隨著培養時間的增加，屬於ACP (solid) → HAp (solid)的轉變路徑。

Calcium phosphate is the main constituent of biological hard tissues in vertebrates. The growth of this mineral phase in vivo occurs in confined space such as cellular vesicles and extracellular matrix. In this work, we investigate the mineralization process of calcium phosphate within phospholipid bilayer vesicles (liposomes). To this aim, liposomes containing calcium/ phosphate ions were prepared by thin film method. TEM images show that the formed nano-crystallites are aggregates with diameter around 50 nm. The XRD data reveal that the precipitate of calcium phosphate is of poor crystalline apatite phase. In addition, the IR spectra suggest the transformation pathway follows the order starting from amorphous calcium phosphate (ACP) and finally to hydroxyapatite (HAp). From solid-state NMR data, ACP and HAp co-exist in the samples and they are in close proximity to each other. A closely-packed model is proposed and the transformation pathway follows: ACP (solid) → HAp (solid)