Rapid, Multistep Dna Hybridisation in Continuous Flow

We present a microfluidic platform for performing fast, continuous flow DNA hybridisation on magnetic particles. Laminar flow streams containing sample oligonucleotides, washing buffer, fluorescently labelled oligonucleotides and washing buffer, were generated in the chamber of a microfluidic chip. Magnetic particles were then introduced into the chamber, and pulled through each of the streams by a permanent magnet placed opposite the particle inlet. DNA hybridisation was successfully performed, as determined by resulting increased fluorescence of the particles. A non-complementary sequence did not yield any signal, showing non-specific binding was minimal. The whole procedure required only several minutes, a significant reduction compared to conventional methods. A detection limit of 20 nM was achieved.