A sensitive nanoporous gold-based electrochemical aptasensor for thrombin detection

An attempt was made in the present paper to develop a nanoporous gold (NPG)-based electrochemical aptasensor for thrombin detection. The substrate electrode NPG was in situ fabricated by a facile one-step square wave potential pulse (SWPP) treatment. The treatment involved repeated gold oxidation-reduction and intensive H-2 bubbles evolution. After 100 min treatment, the active surface area of Au increased greatly (34 times). The electrochemical aptasensor was fabricated using a layer-by-layer assembling strategy. A sandwich structure was formed via thrombin connecting the aptamer-modified NPG and the aptamer-modified Au nanoparticles (AuNPs). The AuNPs was modified with two kinds of single strand DNA (ssDNA). One was aptamer of thrombin, but the other was not, reducing the cross-reaction between thrombin and its aptamer on the same AuNP. The electrochemical signal produced by the [Ru(NH3)(6)](3+) bound to ssDNA via electrostatic interaction was measured by chronocoulometry. Due to the amplification effects of both NPG and AuNPs, this novel NPG-based aptasensor could detect thrombin quantitatively in the range of 0.01-22 nM with a detection limit as low as 30 fM. The present aptasensor also exhibited excellent selectivity, stability and reusability. (C) 2010 Elsevier B.V. All rights reserved.