A label-free impedimetric DNA sensing chip integrated with AC electroosmotic stirring

AC electroosmosis (ACEO) flow and label-free electrochemical impedance spectroscopy are employed to increase the hybridization rate and specifically detect target DNA (tDNA) concentrations. A low-ionic-strength solution, 6.1 mu S/cm 1 mM Tris (pH 9.3), was used to produce ACEO and proved the feasibility of hybridization. Adequate voltage parameters for the simultaneous ACEO driving and DNA hybridization in the 1 mM Tris solution were 1.5 V-pp and 200 Hz. Moreover, an electrode set with a 1:4 ring width-to-disk diameter ratio exhibited a larger ACEO velocity above the disk electrode surface to improve collecting efficiency. The ACEO-integrated DNA sensing chips could reach 90% saturation hybridization within 117 s. The linear range and detection limit of the sensors was 10 aM-10 pM and 10 aM, respectively. The label-free impedimetric DNA sensing chips with integrated ACEO stirring can perform rapid hybridization and highly-sensitive detections to specifically measure tDNA concentrations. (c) 2013 Elsevier B.V. All rights reserved.