Sensitive Electrochemical Detection of Nucleic Acids Following Electrokinetic Enrichment in a Bed of Bioconjugated Beads for Point-of-Care Testing

In this presentation, we demonstrate that ion concentration polarization (ICP) in the presence of fluid flow drives focusing and efficient capture of target nucleic acids within a bed of oligoprobe-conjugated beads. A key finding is that ion conduction along the surface of the bioconjugated beads is the dominant contributor to current to the electrode that drives ICP, under the condition of ICP-induced depletion of ions from the bulk solution. Therefore, hybridization of a target nucleic acid (a polyanion) to the bead surface leads to a shift in the slope of the current-voltage curve. This approach is versatile in that a target nucleic acid can be detected electrically, in the absence of a label, or electrochemically via a label that generates an electroactive product. The resulting approach allows for a plug-and-play nucleic acid sensor using off-the-shelf bioconjugated beads and simple electronics, making it advantageous for point-of-care testing.