Electrical Detection of DNA Nanoballs Using Impedance Spectroscopy in a Microfluidic Chip

Traditional methods of molecular detection often require extensive sample preparation steps, equipment, and reagents which limit applicability, particularly in a resource limited setting. This paper reports a novel method of a digital label-free impedance-based detection of specific DNA/RNA sequences using self-assembling DNA Nanoballs formed by a one-pot reaction by simply adding two compaction oligos to a standard reverse transcriptase loop mediated isothermal amplification (RT-LAMP) reaction. The impedance detection of these compacted DNA nanoballs using gravity driven passive flow in a microfluidic chip with integrated gold electrodes, for the first time, will enable direct label-free detection of specific DNA/RNA sequences in solution without the need for additional labels, tags or beads. We demonstrate the formation and detection of DNA nanoballs using synthetic targets, however, our novel method may be adapted for any DNA sequence and can thus be used as an efficient screening method for various pathogenic sequences and diseases.