Gel Shrinkage in Discontinuous Electrophoresis: How to Stabilize the Electrolyte Boundary in Epitachophoresis - Part 2 - Nongel Solid Support.

In the first part of this study, we have examined the shrinkage of hydrophilic gels during epitachophoresis, an isotachophoresis-like discontinuous electrophoretic technique, applied to concentrate DNA samples. In the present work, we evaluated selected solid porous media (sponges, nanofibers, foamed polymers, membranes, and structured inserts) as alternative anticonvective media. All materials were assessed based on zone shape, ease of creating the boundary between the leading and trailing electrolytes, and the DNA recovery. While nanofibers and most sponges resulted in poor separation or high analyte adsorption, mechanically supported agarose gels and filtration membranes provided sharp dye zones and high DNA recovery. Foamed polymers, especially plasma-treated ultrahigh molecular weight polyethylene, showed the best overall performance. Some rigid open structures (e.g., silica columns or nylon nets) demonstrated potential for large analytes but require further optimization. These results highlight key design considerations for robust, scalable epitachophoresis devices for preparative DNA concentration using solid-state stabilization media.