以掃描式探針顯微術在水溶液中展開單一菌視紫紅質及操控去氧核醣核酸分子

本論文以掃描探針顯微鏡觀察去氧核醣核酸(λ-DNA)和菌視紫紅質(bacteriorhodopsin)在緩衝溶液中的分子影像，並以掃描探針為工具，拉伸單一菌視紫紅質分子及操控單一λ-DNA移至指定位置。掃描式探針顯微鏡雖然具有能在溶液中取得次奈米級的解析度，也能在水溶液中操控樣品的兩項優勢，然而為了降低探針來回掃描對所生物分子成像的干擾，所研究和操控的生物分子必須穩固地固著在平坦的基底上，但卻又希望固著吸力不能改變分子的化學特性，或妨害分子在溶液中的行為。因此本研究以物理性吸附固定生物分子：(1)利用調製緩衝液，以精確控制菌視紫質在雲母表面的靜電排斥力小於凡德瓦力，並以原子力顯微鏡(Atomic Force microscopy)的接觸模式(contact mode)來研究菌視紫紅質分子，並以探針懸臂拉伸菌視紫質，研究單一分子內胺基酸的展開與摺疊過程，探討分子與基底間固著吸附力。(2)利用控制試片電位，操控基底電雙層極性與電荷密度以吸附或去吸附λ-DNA。

關鍵字

菌視紫紅質；去氧核醣核酸；原子力顯微術；電化學掃瞄式穿隧顯微術；操控

並列摘要

We used Scanning Probe Microscopy(SPM) to observe λ-DNA and bacteriorhodopsin (BR) molecule images in the buffer solution, stretch individual BR molecules, and facilitate the movement of λ-DNA to specified positions. SPM is often used to produce images with a subnanometer resolution through a physical scan of a specimen, but it can also be used to manipulate biomolecules within a solution. However, during an SPM scan, the interaction between the probe and the surface may disturb the forces holding the biomolecules. Therefore, the biomolecules must be immobilized on the flat substrate before the scan may proceed. In addition, there is a possibility that the immobilization force will modify the chemical properties of the biomolecules or alter the behavior of the molecule in the solution, which can be prevented through the use of physisorption. In this thesis (1)We adjusted the ion strength and the pH of the buffer solution in order to accurately balance the electrostatic force between the molecules and mica. We used AFM contact mode to image the BR molecules, stretched the BR with a probe to investigate the process of folding and unfolding of amino acids, and discussed the immobilization force between the molecules and mica. (2)We controlled the sample potential in order to manipulate the electric double layer and charge density of the substrate, and then adsorbed or removed λ-DNA.

並列關鍵字

bacteriorhodopsin ； DNA ； AFM ； EC-STM ； manipulate

參考文獻

1 Binnig, G., Rohrer, H., Gerber, C., and Weibel, E., Surface Studies by Scanning Tunneling Microscopy. Phys Rev Lett 49 (1), 57 (1982).

2 Binnig, G., Quate, C. F., and Gerber, C., Atomic Force Microscope. Phys Rev Lett 56 (9), 930 (1986).

3 Martin, Y. and Wickramasinghe, H. K., Magnetic Imaging by Force Microscopy with 1000-a Resolution. Appl Phys Lett 50 (20), 1455 (1987).

4 Heckl, W. M. et al., Characterization of a Covalently Bound Phospholipid on a Graphite Substrate by X-Ray Photoelectron-Spectroscopy and Scanning Tunneling Microscopy. Langmuir 5 (6), 1433 (1989).

5 Lyubchenko, Y. L., Lindsay, S. M., Derose, J. A., and Thundat, T., A Technique for Stable Adhesion of DNA to a Modified Graphite Surface for Imaging by Scanning Tunneling Microscopy. J Vac Sci Technol B 9 (2), 1288 (1991).

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以掃描式探針顯微術在水溶液中展開單一菌視紫紅質及操控去氧核醣核酸分子

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