(142db) Single Chain Dynamics of Submicron Sized Semiflexible and Flexible Biological Polyelectrolytes in Flow Fields

Polyelectrolytes are characterized by charged soft matters bearing ionic groups and accompanying counter-ions, such as water-soluble biomolecules, DNA, and polysaccharides. This implies complication arising from Debye screening effect and high sensitivity to external fields. We investigated conformation and translational diffusion of the single chain of submicron sized biological polyelectrolyte xanthan in solvents by employing coarse-grained Brownian dynamics simulations [1,2]. Our coarse-grained model goes beyond other simulations, which dealt with mainly the long chain of DNA [3,4], as they do not consider simultaneously both the long-range electrostatic and hydrodynamic interactions between pairs of beads. Based on order-disorder transition of polysaccharide backbone, semiflexible and flexible chains can be prepared by native (double strand) and denatured (single strand) xanthan, respectively. Simulation parameters are obtained from the viscometric method of rheology data on each chain. Contrary to conformational properties in uniform flows, the influences by flow strength as well as flow type are evident in both simple shear and extensional-like flows, exhibiting a sigmoidal transition of radius of gyration. Transition to a higher plateau and independence of electrostatic screening can be encountered earlier with increasing flow strength, as a special feature in extensional-like flow. The translational self-diffusion increases with increasing either the flow strength or the electrostatic screening in uniform and simple shear flows. In order to bridge theoretical and experimental approaches, we will present typical results of the single molecule tracking performed on fluorescein-labeled xanthan by applying epi-fluorescence microscopy under controlled flow fields. Present study on conformational dynamics of length and time scales in external flow fields can play an important role in a challenge of design to develop well-suited microfluidic devices.  (This work was supported by the Basic Research Fund (20100021979) and the Converging Research Center (2009-0082136) through the National Research Foundation of Korea.)

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