Optimizing end-labeled free-solution electrophoresis by increasing the hydrodynamic friction of the drag-tag

摘要

We study the electrophoretic separation of polyelectrolytes of varyinglengths by means of end-labeled free-solution electrophoresis (ELFSE). Acoarse-grained molecular dynamics simulation model, using full electrostaticinteractions and a mesoscopic Lattice Boltzmann fluid to account forhydrodynamic interactions, is used to characterize the drag coefficients ofdifferent label types: linear and branched polymeric labels, as well astransiently bound micelles. It is specifically shown that the label's drag coefficient is determined byits hydrodynamic size, and that the drag per label monomer is largest forlinear labels. However, the addition of side chains to a linear label offersthe possibility to increase the hydrodynamic size, and therefore the labelefficiency, without having to increase the linear length of the label, therebysimplifying synthesis. The third class of labels investigated, transientlybound micelles, seems very promising for the usage in ELFSE, as they provide asignificant higher hydrodynamic drag than the other label types. The results are compared to theoretical predictions, and we investigate howthe efficiency of the ELFSE method can be improved by using smartly designeddrag-tags.