Unfolding a single bacteriorhodopsin and manipulating DNA biomolecule with scanning probe microscopy in buffer solutions

• Main Authors: Hao-Chung Ting, 丁浩中
• Other Authors: 張慶瑞
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/57238944911508183463

碩士 === 國立臺灣大學 === 物理研究所 === 96 === 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.