An ultrasensitive label-free electrochemical impedimetric DNA biosensing chip integrated with a DC-biased AC electroosmotic vortex

A label-free electrochemical impedance spectroscopy (EIS)-based DNA biosensing chip is integrated with DC-biased AC electroosmotic (ACEO) stirring using concentric double ring-single disk electrodes to greatly promote the hybridization efficiency of 20-base target DNA (tDNA) fragments. The +0.7 V-biased ACED flow of 3 V-pp and 380 Hz applied at the outer ring electrode (ORE) and inner ring electrode (IRE) can drive the tDNA-containing 1 mM Tris solution from the ORE to the probe's DNA-modified disk electrode (DE) to achieve 90% saturation hybridization within 141 s. The DNA biosensor used Pd-deposited ORE as the pseudo-reference electrode and IRE as the counter electrode for on-chip-type three-electrode EIS measurement, and presented good linearity and repeatability in the range of 1 aM-10 pM and exhibited an ultrasensitive detection limit of 0.5 aM. The label-free EIS-based DNA sensing chips with integrated DC-biased ACED vortex can achieve rapid hybridization, high selectivity and ultrasensitive detection for different tDNA samples. (C) 2014 Elsevier B.V. All rights reserved.