- 學位論文
量子點表面改質與生物分子的鍵結
Quantum Dots Surface Modification and Bio-Conjugation
摘要
本研究成功的利用氫硫基化合物 Mercaptopropionic acid (MPA)與兩性高分子(Poly(maleic anhydride alt-1-tetradecene))來修飾CdSe/ZnS量子點的表面，使水溶性量子點回收率都高達85%以上，改質後的量子效率雖有損失，但也約有50 %。我們也進行水溶性量子點的鹽穩定性探討，發現利用MPA改質的量子點，其鹽穩定性較差，在表面接合蛋白質後可略微提升。而以兩性高分子(Poly(maleic anhydride alt-1-tetradecene))來包覆的量子點，其鹽穩定性甚佳，長期儲存也不易發生聚集。此外，我們也將量子點表面鍵結ssDNA，再將完全互補及single mismatched ssDNA接於玻璃板上，藉由觀察玻璃表面螢光強度來判斷雜合程度，實驗結果顯示single mismatched DNA的雜合程度較完全互補者有明顯的降低，顯示CdSe/ZnS量子點可明確偵測mismatched 的DNA。最後藉由能量轉移 (Fluorescence energy transfer，FRET) 現象，由Förster的理論，我們可計算出螢光基團距離量子點距離不同時所展現的FRET效率，從而可推測紅螢光蛋白的吸附位向與吸附量，經推算可以直接估計出每個量子點表面吸附1個紅螢光蛋白。
並列摘要
CdSe/ZnS quantum dots (Qdots) were made water soluble by surface modification with the help of mercaptopropionic acid (MPA) or a polymer called Poly(maleic anhydride alt-1-tetradecene). Both methods produced soluble Qdot close to 85% recovery, and the quantum yields were both approaching 50%. The stability of soluble Qdots was also under investigation. It was found that MPA modified dots easily aggregated in 0.1 M NaCl, but the polymer coated dots were fairly stable. The covalently bound bovine serium albumin (BSA) increased the stability of Qdots. We also tried to detect the single mismatched ssDNA by Qdot linked ssDNA. It was found that the hybridization efficiency of single mismatched ssDNA was far lower than the completely complementary one. It indicated that Qdots linked ssDNA could accurately detect mismatched ssDNA. By mean of fluorescence resonance energy transfer (FRET) the number of red fluorescence protein (RFP) absorbed on Qdots could be accurately estimated. There are only one RFP molecule adsorbed on each dot. By adopting Forster’s theory the distance between Qdot and fluorescent center can be calculated by FRET efficiency. Therefore, the orientation of RFP on Qdot could be elucidated.