A sensitive and selective thrombin impedimetric aptasensor based on tailored aptamers obtained by solid-phase synthesis

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 impedimetric 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 thrombin in the range of 3–30 ng mL−1and 3–50 ng mL−1for 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.