Sieving mechanisms in polymeric matrices

Abstract

A critical review of the existing theoretical models and experimental evidences for sieving mechanisms during separation of macromolecules, paying particular attention to capillary electrophoresis applications is presented. Gel models (Ogston and reptation) have been successfully applied to highly entangled polymer solutions, where fast and efficient separations can occur. In order to account for the DNA/polymers collision-interaction mechanisms during separation in dilute solutions - characterized by a poorer resolution -, approximated analytical models have been developed. An insight in the mechanism regulating the intermediate case of moderately entangled polymer solutions, for low fields and concentrations of small multiples of the overlap concentration c*, is given by the constraint release approach. This model proposes an upper limit of size separation, increasing with matrix concentration and molecular mass. Finally, the coupling between the reptative motion of the analytes and the effect of matrix constraint release very likely plays a fundamental role in the separation mechanism and requires therefore further and deeper investigation, both theoretically and experimentally.

Matrix conditioning for lengthened capillary DNA sequencing

“…The pulses are designed to be long enough so that relaxation effects of either the DNA or the sieving matrix are insignificant [22]. When choosing pulses, the assumption is made that the electrophoretic mobility of a DNA sequencing fragment does not vary with time at constant E. This same assumption is often made when quantifying results of constant field capillary DNA analysis in solutions of polymers (reviewed in [13,14,[17][18][19][20]). However, this assumption is shown here to be false, at least in the absence of a deliberate erasing of the memory of the preconditioning.…”

“…To interpret observations made during electrophoresis in a polymer solution, the implicit, often unstated assumption is made that the sieving characteristics are independent of time during electrophoresis (reviewed in [17][18][19][20]). However, this assumption was found to be inaccurate when a capillary with POP-6 polymer solution was repeatedly used for capillary DNA fractionation without replacing the polymer solution between fractionations.…”

Microfluidics: Fluid physics at the nanoliter scale

“…Finally, separation techniques, particularly for nucleic acids, occupy a central role in many microfluidic devices. Specific reviews include DNA separation and analysis methods in the microfluidic context ͑Ugaz et al, 2004͒, DNA separation in microfabricated devices ͑Tegenfeldt et al, 2004͒, the theory of polymer separation ͑Viovy, 2000; Slater et al, 2002Slater et al, , 2003Ashton et al, 2003;Sartori et al, 2003͒, andmicrochip-based polymer electrophoresis ͑Bousse et al, 2000;Bruin, 2000;Dolnik et al, 2000͒. Rather than duplicate these efforts, the present review emphasizes the physics of the field over its specific applications, and should complement other physically minded reviews ͑Brody et al., 1996;Beebe et al, 2002;Stone et al, 2004͒. Specifically, we consider fluid physics that occurs within channels with typically ϳ100 m transverse dimension-for reference, 1 nl= ͑100 m͒ 3 .…”

Poly(methylmethacrylate) Microchip Electrophoresis of Proteins Using Linear-poly(acrylamide) Solutions as Separation Matrix

“…Generally, SBPS in CE was performed under the condition that the mobility difference between SDS-PC and EOF was 10 or more. 17 Therefore, the larger proteins than CA could be hardly introduced to the detection point only with difficulty since they should have lower mobility than CA. To separate more SDS-PC, further improvement for decreasing EOF was needed.…”