Resolving DNA in free solution

DNA molecules are usually separated by gel electrophoresis. While gels help resolve DNA, the polymers bring problems to the analysis (e.g., difficulty in automating and poor reproducibility). One way to eliminate these problems completely is to separate DNA in free solutions. However, DNA fragments cannot normally be resolved in a free solution by electrophoresis because the electrophoretic mobilities of these molecules have similar charge-to-mass ratios, especially when the fragments are large. Efforts have been invested in free-solution DNA separations and a number of approaches (e.g., high-performance liquid chromatography, end-labeled free-solution electrophoresis, entropic traps, and DNA prism) have been successfully developed. Very recently, a new technique, called bare narrow capillary-open tubular chromatography (BaNC-OTC), was developed and can resolve a wide range of sizes of DNA in a few minutes. In this article, we review the significant progress on free-solution DNA separations, with emphasis on the most recent, advanced developments. (C) 2012 Elsevier Ltd. All rights reserved.