Localized Single Molecule Isotherms of DNA Molecules at Confined Liquid−solid Interfaces


The study of dynamics and thermodynamics of single biological molecules at confined liquid-solid interfaces is crucially important, especially in the case of low-copy number molecules in a single cell. Using a high-throughput single molecule imaging system and Lagrangian coordinates of single molecule images, we discovered that the local equilibrium isotherms of single ?DNA molecules at a confined liquid-solid interface varied from a stair type for the regions of single or double molecular DNA to a mild “S” type for the regions of triple molecular DNA spots, which does not agree with the conventional equilibrium isotherms in the literature. Single molecule images in time sequence for different ?DNA concentrations were statistically analyzed by measuring preferential partitioning from shearing effects, which were used to measure the local velocity of DNA molecules by directly observing the migration of DNA fluorescence spots for the 12 continuous images. The local linear velocity of hydrodynamic flow was calculated by the Hagen-Poiseuille equation in different microregions with a local Lagrangian approach. The local single molecule isotherms for the tracked molecules in the regions of single, double, or triple molecular DNA layers within the laminar flows were obtained according to the average local velocities of both the stochastic molecule events and the corresponding local Poiseuille flows. A millisecond and microvolume approach to directly determine local single molecule isotherms at confined liquid-solid interfaces was established, and the microspace scale effects on the types of isotherms were discovered. This study may have significant impact on preparations of low-copy number proteins in a single cell, membrane separations, and other bioseparation studies.




Missouri University of Science and Technology. Department of Chemistry
Missouri University of Science and Technology. Environmental Research Center
National Natural Science Foundation (China)

Keywords and Phrases

Bio Separations; Biological Molecules; Confined Liquids; Copy Numbers; Dna Concentrations; Dna Fluorescences; DNA Layers; DNA Molecules; DNA Spots; Equilibrium Isotherms; Hagen-poiseuille Equations; High Throughputs; Hydrodynamic Flows; Lagrangian Coordinates; Local Equilibriums; Local Lagrangian Approaches; Local Linear; Local Velocities; Membrane Separations; Micro-regions; Poiseuille Flows; Scale Effects; Significant Impacts; Single Cells; Single Molecules; Single-molecule Imaging; Time Sequences; Adsorption Isotherms; Atmospheric Temperature; Cell Membranes; DNA; Fluid Dynamics; Genes; Lagrange Multipliers; Laminar Flow; Liquids; Molecules; Nucleic Acids; Optoelectronic Devices; Polymethyl Methacrylates; Phase Interfaces; DNA; Controlled Study; High Throughput Screening; Isotherm; Laminar Flow; Liquid; Solid; Velocity; Viral; Electrophoresis, Capillary; Fluorescent Dyes; Thermodynamics; Time Factors; Thermodynamics

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Article - Journal

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© 2009 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Mar 2009