- 學位論文
利用石英震盪天平及原子力顯微鏡研究圓盤狀微胞吸附去氧核醣核酸作用
DNA Adsorption by Supportted Lipid Bicelles Studied by Quartz Crystal Microbalance and Atomic Force Microscopy
若您是本文的作者，可授權文章由華藝線上圖書館中協助推廣。
摘要
本論文研究利用混合長鏈與短鏈磷脂質分子形成的帶正電荷圓盤形雙層膜吸附在二氧化矽薄膜表面，以研究吸附去氧核醣核酸(DNA)的作用。吸附過程以石英震盪微天平(QCM)做即時監測，並將吸附完成之承載基板用原子力顯微鏡(AFM)做表面結構掃瞄。研究分兩部份，首先利用磷脂分子DPPC與diC7PC以固定比例混合形成圓盤狀微胞並利加入不同量的帶正電膽固醇分子使圓盤形微胞帶正電，探討不同量的正電荷對吸附去氧核醣核酸的影響，從AFM與QCM的結果我們發現當混入一定比例的帶正電膽固醇分子可以穩定脂雙層膜的形成進而不會有堆疊多層吸附的情形。圓盤形微胞吸附在基板的速率隨著微胞中正電荷的膽固醇含量增加而減緩，可能因微胞間電荷斥力較大時互斥，不易漂近表面，受到已吸附的微胞的正電荷排斥。 第二部份則是探討圓盤狀微胞電性對700鹼基對與2000鹼基對 DNA分子吸附作用的影響。DNA分子吸附於圓盤狀微胞大致可分成三階段，第一階段以靜電力作用為主的快速吸附，第二階段為較緩慢的吸附過程，可能因已吸附的DNA分子需要調整成較整齊的排列，第三階段則為較第二階段略快吸附過程，逐漸吸附至飽和值。帶較高正電荷的微胞會較快速且會吸附較多的DNA。研究發現較長DNA分子吸附總量較大及吸附速率較高。
並列摘要
Quartz Crystal Microbalance (QCM) was used in monitoring the DNA adsorption kinetics by cationic lipid nano-disc bicelles supported by silicon dioxide substrate. Atomic Force Microscope (AFM) was also used in examining the surface morphology of the substrate with adsorbed DNA. The nano-disc bicelles were formed by mixing long-chain lipid DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) with the short-chain lipid diC7PC (1,2-diheptanoyl-sn-glycero-3-phosphocholine), and doped with different amounts of cationic lipid DC-Cholesterol. By doping cationic lipids from 15% to 50% of the long chain lipids, only single layer of bicelles are adsorbed on the silicon dioxide surface with a surface coverage of from 71% to 77% as estimated from the adsorbed mass. As for the DNA adsorption by bicelles, it is found the adsorption process can be divided into three distinctive stages. In the beginning, there is a very fast adsorption stage lasting for about 30 seconds to reach about 15% to 50% of the equilibrium values for 15% to 50% DC-Cholesterol doped bicelles. This fast adsorption stage is followed by a much slower adsorption stage for a few minutes. It is likely that the DNA adsorbed in the fast adsorption stage need to rearrange their distribution on the surface to form more ordered and compact structure. Finally a slow adsorption stage will lead to the equilibrium state in about 30 minutes. For the fast adsorption stage, the DNA adsorption rate constant is higher for higher charge doping percentage bicelles and also for longer DNA. For the second and third adsorption stages, the DNA adsorption rate constants may differ from each other but are all similar.
參考文獻
[1] Dobrynin, A. V.; Rubinstein, M. Prog. Polym. Sci. 2005,30, 1049–1118
[3] Dobrynin, A. V., J. Chem. Phys. 2001, 18, 8145–8153
[4] Cheng, H.; de la Cruz, M. O. J. Chem. Phys. 2003, 23, 12635–12644
[5] Wenzel, A.; Antonietti, M., Adv. Mater. 1997,6 , 487–490
[7] Fang, Y.; Yang, J., J. Phys. Chem. B. 1997, 101, 441–449