Adsorption of single DNA molecules at the water/fused-silica interface

Adsorption of single DNA molecules at the water/fused-silica interface
Available online 19 October 2006
Slavica Isailovica, Hung-Wing Lia and Edward S. Yeung, a
Journal of Chromatography A
Volume 1150, Issues 1-2, 25 May 2007
Copyright ? 2006 Elsevier B.V. All rights reserved.
aAmes Laboratory-USDOE and Department of Chemistry, Iowa State University, Ames, IA 50011, United States
We applied total internal reflection fluorescence microscopy (TIRFM) to study intermolecular interactions at the water/fused-silica interface at the single-molecule level. Real-time molecular motion at the interface was recorded to reveal adsorption behavior and conformational dynamics of three DNAs with sticky ends of different numbers of unpaired bases. Features of DNA motion at the interface, such as evanescent-field residence time, linear velocity and frequency of adsorption/desorption events were measured to assess the relative affinities of the oligonucleotides for the surface. The general trend of stronger interaction with the surface for longer sticky ends confirmed hydrophobic interaction and hydrogen bonding as the driving forces of DNA adsorption to fused-silica at pH 5. For DNAs of different sizes, different conformational dynamics and the accessibility of sticky ends give rise to a nonlinear relationship with respect to affinity. Such information may prove valuable for chromatography studies as well as for the design of DNA microarrays and drug delivery systems.
Keywords: Adsorption; DNA; Fused-silica; Single-molecule
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