Electrophoretic dynamic

D. M. Heuer, S. Saha, and L. A. Archer. Electrophoretic dynamics of large DNA stars in polymer solutions and gels. Electrophoresis, 24 (2003), 3314-3322. 

Vaidya, D Diamond, SL Nitsche, JM Kofke, DA, Potential for Use of Liquid Crystals as Dynamically Tunable Electrophoretic Media, AIChE Journal 43, 1366, 1997. 

Rawjee, Y. Y and Vigh, Gy., Efficiency optimization in capillary electrophoretic chiral separations using dynamic mobility matching, Anal. Chem., 66,3777,1994. 

The dynamic range of protein expression represents a main obstacle since abundant proteins are seldom of interest and others such as transcription factors are only present in a few copies. There is no detector that is able to visualize all proteins at the same time so that prefractionation and the investigation of subproteomes is required. In fact, pre-MS sample preparation techniques exploiting electrophoretic, chromatographic, or chemical properties of the analyte are often the bottleneck of proteomics. 

In order to influence a migration it is obvious that one can alter the charge of the compounds, the viscosity of the medium and the dynamic radius of the compounds. According to Eq. 17.5, the electrophoretic mobility is the proportionality factor in the linear relationship of the migration velocity and the electric field strength... 

Using and S, the translational friction coefficient and the electrophoretic mobility can be calculated by simply replacing G by in the respective formulas. Before we proceed to do this, we present the collective dynamics of monomer density and counterions. 

Although the theory of polyelectrolyte dynamics reviewed here provides approximate crossover formulas for the experimentally measured diffusion coefficients, electrophoretic mobility, and viscosity, the validity of the formulas remains to be established. In spite of the success of one unifying conceptual framework to provide valid asymptotic results, in qualitative agreement with experimental facts, it is desirable to establish quantitative validity. This requires (a) gathering of experimental data on well-characterized polyelectrolyte solutions and (b) obtaining the relationships between the various transport coefficients. Such data are not currently available, and experiments of this type are out of fashion. In addition to these experimental challenges, there are many theoretical issues that need further elaboration. A few of these are the following ... 

Mechanistic Ideas. The ordinary-extraordinary transition has also been observed in solutions of dinucleosomal DNA fragments (350 bp) by Schmitz and Lu (12.). Fast and slow relaxation times have been observed as functions of polymer concentration in solutions of single-stranded poly(adenylic acid) (13 14), but these experiments were conducted at relatively high salt and are interpreted as a transition between dilute and semidilute regimes. The ordinary-extraordinary transition has also been observed in low-salt solutions of poly(L-lysine) (15). and poly(styrene sulfonate) (16,17). In poly(L-lysine), which is the best-studied case, the transition is detected only by QLS, which measures the mutual diffusion coefficient. The tracer diffusion coefficient (12), electrical conductivity (12.) / electrophoretic mobility (18.20.21) and intrinsic viscosity (22) do not show the same profound change. It appears that the transition is a manifestation of collective particle dynamics mediated by long-range forces but the mechanistic details of the phenomenon are quite obscure. 

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