Dielectrophoretic Sorting of DNA Molecules by Size in a Microfluidic Platform

Science Center A154

Size-dependent sorting and manipulation of nucleic acids is essential for powerful bioanalysis and biotechnology methods, including genetic sequencing, clinical diagnostics, and DNA nanofabrication. In particular, promising next generation sequencing (NGS) methods demand target nucleic acids to be within certain length ranges from several hundred basepairs (bp) to several kbp. However, achieving rapid, high-efficiency separation of nucleic acids by size still presents considerable challenges. Traditional nucleic acid separation methods (including gel electrophoresis) typically offer limited throughput, resolution, and/or dynamic range; these technologies have not kept pace with the rapidly growing technical demands of emerging bioanalysis platforms. In this work, we develop a high-efficiency microfluidic platform to sort diverse DNA analytes by size under continuous flow. The device, employing insulator-based dielectrophoresis (iDEP), creates size-selective forces on dielectric analytes by imposing spatial gradients in electric fields. We demonstrate sorting of both plasmid and genomic DNA molecules ranging in size from 1-48.5 kbp, and characterize analyte behavior using semiautomated image analysis. The sorting behavior of DNA is strongly dependent on applied potential and frequency, enabling adjustable operation for different analytes. These results support the potential for robust and efficient manipulation of nucleic acids by size for a variety of downstream analysis applications.