Label-free electrical quantification of the dielectrophoretic response of DNA

Abstract

A purely electrical sensing scheme is presented that determines the concentration of macromolecules in solution by measuring the capacitance between planar microelectrodes. Concentrations of DNA in the ng/mL range have been used in samples of 1 L volume. The method has been applied to the characterisation of the dielectrophoretic response of DNA without the need for any chemical modifications. The influence of electrical parameters like duty cycle, voltage and frequency has been investigated. The results are in good agreement with data from dielectrophoretic studies on fluorescently labelled DNA. Extension of the method down to the single molecule level appears feasible.

Dielectrophoresis of DNA: Quantification by impedance measurements

“…Such an interruption should last for about the characteristic time of this decay. In a similar study 32 this has been determined to about 30 s for slightly different electrodes.…”

“…This principle was later employed in a more sensitive system with a capacitance bridge, an independent signal source, and with switching by relays. 32 In the present work this enhanced system is used for studying the influence of DEP frequency, DNA concentration, and molecular weight on the dielectrophoretic response of DNA.…”

DNA dielectrophoresis: Theory and applications a review

“…Another monitoring method exploits impedance or capacity measurements, which both are strongly dependent on the existence of charged objects in the measurement area . Thus, concentrations of biomolecules can be detected by these methods.…”

“…Henning et al. measured the concentration of DNA by monitoring the capacitance between interdigitated electrodes . Via the capacitance measurement they determined the dielectrophoretic response of DNA without the need for any chemical modification of the analyte, making fluorescent labeling obsolete.…”

Enhancing the Performance of Surface-based Biosensors by AC Electrokinetic Effects - a Review

“…Capacitance measurement is employed by means of detecting and quantifying the polarization response of DNA as the cell passed through a 1 kHz electric field. Capacitance detection of DNA in solution has been applied by measuring the capacitance change between the planar microelectrodes (Henning et al, 2008). Total DNA content of a cell has also been quantified by using capacitance cytometry, a termed coined by the authors to describe the linear relationship between the AC-capacitance and the DNA content (Sohn et al, 2000).…”