Size Fractionation of Milliliter DNA Samples in Minutes Controlled by an Electric Field of ∼10 V

Abstract

DNA size fractionation is an essential tool in molecular biology, which is used to isolate targets in a mixture characterized by a broad molecular weight (MW) distribution. Microfluidics was thought to provide opportunity to create devices capable of enhancing and speeding up the classical fractionation processes. However, this conjecture met limited success due to the low mass and/or volume throughput of these technologies. We describe the µLAF (µLaboratory for DNA Fractionation) technology for DNA size selection based on the stacking of molecules on films of ~100 µm in thickness with 10 5 pores of ~2 µm in diameter. Size selection is achieved by controlling the regime of electrohydrodynamic migration in the pores through the temporal modulation of an electric field. This technology allows the processing of milliliter-scale samples containing a DNA mass of several hundreds of ng within ~10 minutes, and the selection of DNA in virtually any size window spanning 200 to 1000 bp. We demonstrate that one operation suffices to fractionate sheared genomic DNA in up to six fractions with collection efficiencies of ~20-40 % and enrichment factors of ~1.5-3 fold. These performances compare favorably in terms of speed and versatility to those of current standards.