Influence of DNA Concentration on the Interfacial Electrode Impedance

Abstract

Sensitive and accurate DNA quantification is an essential step in most DNA analyses, especially in analysis of a small amount of DNA. Instead of typical DNA quantification methods (i.e., UV spectrometry, fluorometry, and quantitative polymerase chain reaction), electrical impedance spectroscopy has recently been investigated for label-free and efficient quantification of DNA. In this study, quantification of DNA in solution was investigated using electrical impedance spectroscopy without pre-processing, including the modification of the electrode surface and immobilization of DNA onto the electrode. The results showed that the measured impedance spectra were in agreement with a designed equivalent circuit model, and that the extrapolated parameters of interfacial electrode impedance were dependent on DNA concentration. The impedance measured at 1 and 10 kHz showed good correlation with DNA concentration (R-2 > 0.95), with a dynamic range of detection from 0.01 pg/mu l to 100 ng/mu l. Based on the results, it is expected to utilize impedance spectroscopy for the real-time and label-free characterization of DNA concentration with high sensitivity and low operation cost.