Structure and Dynamics of DNA Adsorbed on a Supported Cationic Lipid Membrane

• Main Authors: Chen-Ming Chang, 張宸銘
• Other Authors: Wen-Tau Juan
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/19672354645065815319

碩士 === 國立中央大學 === 物理研究所 === 100 === Relaxation of the chain-like DNA molecules upon adsorption on a supported cationic lipid membrane is time-resolved by direct imaging. Following the stochastic landing onto the membrane at a nearly spherical initial state, these DNA coils gradually relax and expand their apparent size in a highly anisotropic fashion. By using membranes with different charge densities, we show that the time evolution of the ensemble-averaged apparent size of the DNA molecules can be characterized by a generic exponential function despite significant variation between individual events. The exponential fitting also determines the primary time scale in the relaxation process, which is faster for DNA adsorbed on membranes with lower charge density. Examination on the conformational change of single DNA molecules on different membranes reveals non-trivial interaction between the adsorbed DNA molecule and the host membrane, with DNA relaxing through more anisotropic extrusions on membranes with higher charge density. The ensemble-averaged square displacement of the center-of-mass of the DNA molecules, which are found to be rescaled by the primary time scale, can be another indicator of the relaxation process.