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Vol. 88, Issue 2, February 2008, pp.31-39




Improving Probe Immobilization for Label-Free Capacitive Detection of DNA Hybridization on Microfabricated Gold Electrodes


Sandro Carraraa*, Vijayender Kumar Bhallaa, Claudio Stagnia,b, Luca Beninib, Bruno Riccòb, Bruno Samorìa

aBiochemistry Department, University of Bologna, Via Irnerio, 48 Bologna, Italy
bDEIS Department, University of Bologna, Viale Risorgimento 2, Bologna, Italy

*The corresponding author is now in Swiss Federal Institute of Technology – Lausanne (EPFL) - EPFL IC ISIM LSI1 - INF 333 (Bâtiment INF) Station 14 CH-1015 Lausanne
E-mail: sandro.carrara@epfl.ch


Received: 25 January 2008   /Accepted: 22 February 2008   /Published: 26 February 2008


Abstract: Alternative approaches to labeled optical detection for DNA arrays are actively investigated for low-cost point-of-care applications. In this domain, label-free capacitive detection is one of the most intensely studied techniques. It is based on the idea to detect the Helmholtz  ion layer displacements when molecular recognition occurs at the electrodes/solution interface. The sensing layer is usually prepared by using thiols terminated DNA single-strength oligonucleotide probes on top of the sensor electrodes. However, published data shows evident time drift, which greatly complicates signal conditioning and processing and ultimately increases the uncertainty in DNA recognition sensing. The aim of this work is to show that newly developed ethylene-glycol functionalized alkanethiols greatly reduce time drift, thereby significantly improving capacitance based label-free detection of DNA.


Keywords: DNA biochip, Capacitance detection, Ion layering, ethylene-glycol Thiols


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