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Cross-Stream Migration of Chain Molecules in Nanofluidic Channels

Rajesh Khare, Department of Chemical Engineering, Texas Tech University, P. O. Box 43121, Lubbock, TX 79409-3121

The phenomenon of flow induced cross-stream migration of polymer chains in nanochannels has suggested the possibility of developing nanofluidic devices for novel DNA separation and sequencing operations. Our recent work [1] on molecular dynamics simulations of shear flow of dilute polymer solutions in nanochannels has shown that the cross-stream chain migration process is governed by three mechanisms: (a) chain-wall hydrodynamics (b) thermal diffusion and (c) gradients in chain mobility.

In that work, a bead-spring model was used for the polymer chain and the solvent was represented using a coarse grained model with the interactions between various species in the system being modeled by a purely repulsive Lennard-Jones potential. The diffusion and hydrodynamic effects in the model system were determined by these intermolecular interactions. In this work, we study shear flow of dilute polymer solutions in nanochannels by employing more realistic models for the polymer chain and the solvent molecules. Both static and dynamic properties of the system are used to assess the ability of these molecular models for representing the flow of a DNA solution in a nanochannel. Our results are used to determine the relative importance of a variety of factors such as the solvent quality, chain length and the channel dimensions on the cross-stream migration phenomenon in nanofluidic devices.


[1] Khare, R.; Graham, M. D.; de Pablo, J. J.; “Cross-stream migration of flexible molecules in a nanochannel”, submitted.