Label-free electrical detection of nucleic acids following electrokinetic enrichment for point-of-care testing

Sensors that leverage the influence of a biorecognition event on charge transport, such as field-effect transistors and nanoporous membranes, are among the most sensitive because they translate localized binding into a change in a system-scale property. However, fabrication and custom functionalization of these sensors is not trivial, and their integration with protocols that pre-enrich target species and facilitate their transport to the biorecognition site is an active area of research. 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 packed 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. 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. 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.



Robbyn Anand (Iowa State University)