Thermophoresis of DNA in micro-channel

• Main Authors: Shin-pin Lin, 林世彬
• Other Authors: Chan-chi Keung
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/11026304306754870808

碩士 === 國立中央大學 === 物理研究所 === 98 === The motion of DNA in micro-channels due to thermophoresis is studied. 48kbp λ-DNA, 166kbp T4-DNA and 400bp DNA are used. They are tagged by fluorescent YoYo-1 molecules and placed in a micro-sized channel. An infrared laser is used to heat up the system forming a temperature gradient inside the channels. The DNA concentration gradient is then measured by recording the fluorescence intensity profiles of the YoYo-1. The measured DNA concentration profiles are found to be in good agreement with our numerical model fitting in which diffusion and thermophoretic fluxes are considered. Both the apparent Soret coefficient (ST*) and diffusion constant of DNA can be obtained from these numerical model fittings. We define the ST*=ΔT0ST.ΔT0 is the temperature rise of the heating spot. ST is Soret coefficient defined as ST=DT/D when DT is the thermal diffusion coefficient and D is the usual self-diffusion constant. The purpose of this thesis is to study the effects of different capillary tube diameters, lengths of DNA, heating powers, concentration of nano-gold and concentration of spermidine on the properties of DNA thermophoresis. We find that a) diffusion constant and apparent Soret coefficient depend on the ratio of diameter of capillary tube to radius of gyration of DNA b) diffusion constant and Soret coefficient are independent of heating powers when diameter of capillary tube is bigger than radius of gyration of DNA. c) Spermidine will increase the diffusion constant of the DNA and decrease Soret coefficient with the increase of the concentration of spermidine d) Nano-gold will increase the diffusion constant of the DNA but have little effect on the apparent Soret coefficient with the increase of the concentration of nano-gold.