| Summary: | 碩士 === 明志科技大學 === 機電工程研究所 === 101 === Deoxyribonucleic acid (DNA) is the hereditary material of the organism, and it has the double helix structure. There is a direct relationship between the change of the DNA double helix structure and the biological function, so the study of DNA is important for the genetic evolution. This study combined reverse fluorescence microscopy, micro-flow pump and miniature electro-magnet to measure the extension of the lambda-DNA molecules. One used the photolithography process to fabricate the micro-flow channel, and the micro-coil was produced by using the winding method. The magnetic field distribution of the miniature magnet was simulated by the software, COMSOL. In the biological experiment, the primers were used. One end of the primer was fixed to the evaporated gold thin film layer on the glass surface, and the lambda-DNA molecules were hybridized to the primers. And another end of the primer was fixed to the magnetic bead that coated avidin, and its diameter was 2.8 μm. Then one used the magnetic tweezers, the magnetic force generated by the current increasing gradually, to find the relationship between the force and tension of DNA before the DNA was pulled apart, thus providing the basis of biological applications.
Based on the experimental result of the designed miniature electro-magnet and lambda-DNA molecules, the magnetic field was 248.6 Gauss when 0.5 A was used and it could produce 20 pN for the magnetic bead with a diameter of 2.8 μm. The thermocouple was used to measure the temperature of the miniature magnet, and it could be 61.3 °C, but the effect on the buffer was slight because of the micro channel thickness. When the temperature of the buffer was 25 °C and there is no magnetic field, the average length of lambda-DNA molecules was 1.8 μm in the buffer. The extension of lambda-DNA molecules was 7.12 μm in the magnetic field 248.6 Gauss, and the coefficient of elasticity was 2.83×10−6 N/m. Then, the buffer temperature was increased to 45 °C by the hot plate and there is no magnetic field, the average length of lambda-DNA molecules was 4.5 μm. The average extension of lambda-DNA molecules was 11.93 μm, and the average total length was 16.43 μm in the magnetic field 248.6 Gauss, and the coefficient of elasticity was 1.70×10−6 N/m. In experimental results, the average length of lambda-DNA molecule was increased at increasing the temperature without magnetic field, the coefficient of elasticity was decreased when the temperature was increased. When the temperature was heated to 45 °C, the hydrogen bonds of the lambda-DNA molecules were weaker, and it was easier to stretch. A miniature electro-magnet was proposed to manipulate the lambda-DNA molecules, and the results of this study could be contributed to the biomedical detection.
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