Abstract
The dynamic behavior of DNA molecules, when immobilized on DNA microarrays, has puzzled the gene chip researchers .In this study, we used biotin-streptavidin interaction binding to the glass surface at the one end of DNA. Finally, we'll try to distinguish that whether DNA is like seaweed wavering in the solution or like a rope sticking on the surface of glass. The two modes have quite different hybridization efficiency. For fluorescence labeling, quantum dot(Qdot) is a novel fluorescent platform that can emit the fluorescence continually and stably.The TIRF is used to measure the vertical location of fluorescence dye. We measure the TIRF signal of Qdot labeled 2834 bp DNA molecules that were immobilized on the coverslip surface via biotin-streptavidin, and we can estimate the position of Qdot by Gaussian distribution. The result shows that DNA molecules behave like seaweeds and static in the solution, or swing in the particular two position on bsa-biotin coated surface. This phenomenon maybe be caused by hot spot on BSA-biotin coated surface. Therfore, we use PEG-biotin to coat surface to prevent DNA back and forth swing in the particular two position.