Pulsed electrophoresis mechanism

Some future developments should include applying pulsed electrophoresis to studies of very small DNA molecules, proteins, macromolecular complexes, cells and synthetic polymers. Fully understanding the physical mechanisms responsible for pulsed electrophoretic fractionation should enable researchers to extend resolution to even larger DNA molecules and fully generalize use of this new electrophoretic effect. 

The mechanism by which large DNA molecules are separated based upon their molecular weights during steady field or pulsed held agarose gel electrophoresis is not well understood. The prevalent view is that the DNA migrates through the gel by snakelike movements and that the external electric held does not in any way orient the matrix [7],... 

Solignac and Gijs [4] have presented a simple capillary electrophoresis microsystem in which the sample is injected hydrodynamically using a pressure pulse. This approach can transfer a sample solution without electric bias, in contrast to a classical electrokinetic injection, in which the magnitude of the electric field in the sample reservoir in combination with variations in electrophoretic mobility can lead to a biased injection. The sample can be loaded using a well controlled and variable pressure pulse (0.1 - 1.0 s) generated by the mechanical actuation of a flexible membrane placed on the sample reservoir... 

Hammond, etal. studied monodisperse 167 kbpT2 DNA undergoing pulsed-field electrophoresis in 0.01-0.1 % wlw hydroxyethylcellulose(19). Oscillating fields have less effect on electrophoretic motion when the matrix concentration is small. The conformation fluctuations reported by Shi, et al, continued to be seen(16). The observed mechanics of DNA migration did not differ qualitatively between nominally dilute and and nominally semidilute matrix solutions. Hammond, et al concluded that there exists a unified treatment of DNA electrophoresis that covers dilute and nondilute solutions, and steady and pulsed applied electric fields. 

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