Please cite this article in press as: N. Meini, et al., A sensitive and selective thrombin impedimetric aptasensor based on tailored aptamers obtained by solid-phase synthesis, Sens. Actuators B: Chem. (2012), doi:10.1016/j.snb.2012.03.046 ARTICLE IN PRESS G Model SNB-13998; No. of Pages 6 Sensors and Actuators B xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Sensors and Actuators B: Chemical journa l h o mepage: www.elsevier.com/locate/snb A sensitive and selective thrombin impedimetric aptasensor based on tailored aptamers obtained by solid-phase synthesis N. Meini a,b , C. Farre a , C. Chaix a , R. Kherrat b , S. Dzyadevych c , N. Jaffrezic-Renault a,∗ a University of Lyon, Laboratory of Analytical Chemistry, Claude Bernard University Lyon 1, 43 Boulevard 11 November 1918, 69622 Villeurbanne Cedex, France b Laboratory of Environmental Engineering, Badji Mokhtar University Annaba, BP 12, Annaba 23000 Algeria c Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Zabolotnogo St., Kiev 03143, Ukraine a r t i c l e i n f o Article history: Received 14 January 2012 Received in revised form 29 February 2012 Accepted 14 March 2012 Available online xxx Keywords: Aptasensor Aptamer Thrombin Electrochemical impedance spectroscopy Phosphoramidite synthons a b s t r a c t The aim of the present work is to show the interest of a generic concept of aptamers directly obtained through a supported synthesis, using phosphoramidite synthons, for biosensor application. By that way, we were able to tailor the anchoring groups and specific spacers. The concept is validated on an impedi- metric aptasensor for detection of thrombin. Two aptamer sequences, selected from literature (15 and 29 mers), were synthesized with a multi-thiol modification at one extremity. After their grafting on gold electrode, the faradic electrochemical impedance measurements allow the direct detection of throm- bin in the range of 3–30 ng mL -1 and 3–50 ng mL -1 for 15 meraptamer and 29 meraptamer respectively, with a detection limit of 3.1 ng mL -1 (80 pmol/l) for both sequences. This study demonstrates that these aptasensors exhibit high sensitivity (higher sensitivity for 29 meraptamer), high selectivity (compared to a model protein, BSA), stability and reproducibility. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Aptamers (the term “aptamer” derives from aptus that means “to fit”) are single-stranded oligonucleotides which are selected from combinatorial libraries through in vitro SELEX (systematic evolution of ligands by exponential enrichment, a combinatorial chemistry technique in molecular biology for selecting oligonu- cleotides that specifically bind to a target ligand or ligands). SELEX is a process for isolating high affinity ligands, referred to as aptamers, from random-sequence nucleic acid libraries [1,2]. Their develop- ment has been growing as evidenced by the increasing number of scientific publications on this subject since 2004 with over 2000 publications, including about 250 reviews, resulting from a SciFinder search in just a two year period (2009–2010) [3]. Aptamers are often called “synthetic antibodies” and can mimic antibodies in a number of applications [4]. Aptamers present some advantages compared to antibodies, such as relatively easy pro- duction, multiple possibilities of modification, specific binding, high stability, long-term storage and undergoes reversible ther- modynamic denaturation [3]. Aptamers find their application as biorecognition elements in different analytical methods: chro- matography, capillary electrophoresis, mass spectrometry as well as in biosensors design [5]. Biosensors present advantages due ∗ Corresponding author. Tel.: +33 472448306; fax: +33 472431206. E-mail address: nicole.jaffrezic@univ-lyon1.fr (N. Jaffrezic-Renault). to their inherent specificity, simplicity, relative low cost, rapid response, allowing continuous monitoring. Aptasensors are of con- siderable interest due to their application in detection practically unlimited kind of compounds, therefore, they provide new alter- natives in clinical diagnostic, environment and food analysis. Since electrochemical detection with aptamers appeared in literatures several years ago, the study of electrochemical aptasensors based on redox-probe have been the subject of several reviews [4,6]. Thrombin, a “trypsine-like” serine protease protein with a molecular weight of 36,000 Da, plays important role in the coag- ulation cascade, thrombosis and haemostasis. It converts soluble fibrinogen into insoluble strands of fibrin, as well as it catalyzes many other coagulation-related reactions. Beyond its key role in the dynamic process of thrombus formation, thrombin has a pro- nounced pro-inflammatory character, which may influence the onset and progression of atherosclerosis. Acting via its specific cell membrane receptors (protease activated receptors: PAR-1, PAR-3 and PAR-4), which are abundantly expressed in all arterial vessel wall constituents, thrombin has the potential to exert pro- atherogenic actions such as inflammation, leukocyte recruitment into the atherosclerotic plaque, enhanced oxidative stress, migra- tion and proliferation of vascular smooth muscle cells, apoptosis and angiogenesis. The aim of the present work is to show the interest of a generic concept of aptamers directly obtained through a supported synthe- sis, using phosphoramidite synthons for biosensor application. By that way, we will be able to tailor the anchoring groups and specific 0925-4005/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2012.03.046