DNA分子在奈米流道中的運動行為

Abstract

The objective of this thesis is to study the dynamic properties of DNA molecules in nanofluidic slits (nanoslits). The nanoslits were fabricated by standard photolithography with various depths (h~ 97, 58, 47, 40, 30, and 20 nm) on two types of fused silica, each with resistivity of 1012 and 108 ohm-cm, respectively. These devices were bound by a PSQ polymer layer spin-coated on a cover glass after an oxygen plasma surface treatment. By taking fluorescence images of single DNA molecules inside a nanoslit, we studied polymer dynamics via conformational analysis and the time correlation function in these confined nanofluidic environments. We first compare the two sets of experimental results performed on different fused silica substrates and find the diffusivity of DNA molecules in the low-resistivity substrate. Then, we compare the diffusivity of the DNA molecules in the high-resistivity substrate devices with the work done by Strychalski et al. whose nanoslits were fabricated on fused silica substrate and sealed by fused silica cover glass through thermal fusion bonding. We found that the diffusivity of the DNA molecules in our device is smaller than that in when the depth of slits is below 40 nm. Our results suggest that the surface properties of the substrates affect the dynamics of DNA molecules in the strong confinement regime where the channel depth is less than, say, 50 nm. On the other hand, we found the relaxation time increases with respect to decreasing channel depth in the Odijk regime and this observation is in contrary to the results reported by Bonthuis et al..