Gel Shrinkage in Discontinuous Electrophoresis - How to Stabilize the Electrolyte Boundary in Epitachophoresis - Part 1 - Gel Selection

Sep 29, 2026

Gel electrophoresis is typically performed in a single electrolyte system. During development of epitachophoresis for large-volume DNA concentration, which uses a discontinuous electrolyte system, gels can shrink as the leading electrolyte (LE) and trailing electrolyte (TE) boundary moves along the gel. Stabilizing this boundary is essential for analyte focusing in tens-of-milliliters samples. The study evaluated agarose and polyacrylamide stabilization media, optimizing agarose with low electroosmotic flow by tuning gel concentration, electrolytes, pH, and adding Ba2+ ions to reduce deformation from thermal and electrokinetic effects. Simulations implicated pH gradients at the LE/TE interface as a cause. Buffer and pH control, including specific counterions, proved critical. Optimized agarose achieved up to 100% DNA recovery, while polyacrylamide resisted shrinkage but limited large DNA concentration by sieving effects.

LanguageEnglish

CategoryResearch & Report

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Pages9

Reading Time23 min

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Abstract

Introduction

Epitachophoresis overview

Importance of LE/TE interface stabilization

Strategies and gel-based approaches

Experimental/Materials and Methods

This article is licensed under CC-BY 4.0 [http://pubs.acs.org/journal/acsodf](http://pubs.acs.org/journal/acsodf) Article Gel Shrinkage in Discontinuous Electrophoresis: How to Stabilize the Electrolyte Boundary in Epitachophoresis􀀁Part 1􀀁Gel Selection Vanda Kocianová, Ivona Vorá̌cová, * Doo Soo Chung, and Frantǐsek Foret Cite This: ACS Omega 2025, 10, 59513−59521 Read Online | | | | | | | | --- | --- | --- | --- | --- | --- | | ACCESS | Metrics & More | | Article Recommendations | | *sı Supporting Information | ABSTRACT: Gel electrophoresis is typically performed in a single electrolyte system. During the development of epitachophoresis for large-volume DNA concentration, which employs a discontinuous electrolyte system, we found that some gels tend to shrink significantly as the boundary between the leading electrolyte (LE) and trailing electrolyte (TE) moves along the gel. Effective stabilization of this boundary is crucial for analyte focusing, particularly in systems processing tens of milliliters of a sample. This study systematically evaluated various gel stabilization media􀀁including agarosebased gels (NEEO (no electroendosmosis), IsoGel, pulsed-field electrophoresis gel) and polyacrylamide gels􀀁based on their ability to maintain a stable LE/TE boundary, minimize gel shrinkage, and maximize DNA recovery. Agarose gels with low electroosmotic flow were optimized by adjusting the gel concentration, electrolyte composition, and pH and by incorporating Ba2+ ions to reduce gel deformation caused by thermal and electrokinetic effects. Computer simulations highlighted pH gradients atthe LE/TE interface as a key factor contributing to gel shrinkage. The study also revealed that careful control of the buffer composition and pH, especially when Tris, Bis-Tris, and Bis-Tris propane counterions are used, is essential for stable separation and reproducible DNA recovery. Optimal conditions for agarose gels yielded up to 100% DNA recovery, as confirmed by fluorescencebased quantification and capillary electrophoresis. Polyacrylamide gel demonstrated mechanical stability without shrinkage; however, significant sieving effects hindered the effective concentration of large DNA fragments, limiting its applicability. Overall, agarose gels designed for pulsed-field electrophoresis and optimized NEEO agarose formulations provided the best balance of stability, low analyte interaction, and high recovery efficiency for epitachophoretic DNA concentration. This work summarizes practical approaches to LE/TE interface stabilization, which is critical for large-scale biomolecular separations by epitachophoresis. ■ INTRODUCTION Epitachophoresis (ETP) is an advanced electrophoretic technique derived from isotachophoresis (ITP), distinguished by its unique circular design.1 One of the primary advantages of ETP is its ability to efficiently separate, concentrate, and purify large volumes of complex biological samples􀀁ranging from hundreds of microliters to several milliliters􀀁in approximately 1 h. The technique is also notable for its straightforward scalability, simple device setup, and flexibility in handling a wide range of charged analytes.2−4 A critical factor influencing the performance of both ITP and ETP is stabilization of the interface between the leading electrolyte (LE) and the trailing electrolyte (TE) . This interface is essential for the formation of distinct, focused analyte zones based on the electrophoretic mobilities of the analytes.5 A stable LE/TE boundary ensures high resolution, prevents zone dispersion, minimizes turbulence, and enhances the reproducibility. Achieving such stabilization in capillary separations typically involves optimizing the electrolyte composition, incorporating gels or viscous media, maintaining precise control of the electric field, and designing appropriate channels or capillaries.5 In the context of ETP, stabilization of the LE/TE boundary presents a greater challe

FAQs

Why does gel shrinkage occur during epitachophoresis with a discontinuous electrolyte system?

Gel shrinkage is observed as the LE/TE boundary moves along the gel. The study identifies pH gradients at the LE/TE interface as a key contributor to shrinkage.

Which stabilization approach best supports DNA recovery while minimizing gel deformation?

Agarose gels with low electroosmotic flow were optimized by adjusting gel concentration, electrolyte composition, and pH, and by incorporating Ba2+ ions to reduce thermal and electrokinetic deformation, enabling up to 100% DNA recovery.

Why is polyacrylamide gel less effective for concentrating large DNA fragments?

Polyacrylamide gel provides mechanical stability without shrinkage, but sieving effects hinder effective concentration of large DNA fragments, limiting its applicability.

Sep 29, 2026

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