An electrochemiluminescence aptasensor for thrombin using graphene oxide to immobilize the aptamer and the intercalated Ru(phen)32+ probe

The immobilization of aptamer and the introduction of signal molecule are two keys for the development of electrochemiluminescence (ECL) aptasensor. Herein, the immobilization strategy with graphene oxide (GO) and a functional oligonucleotide (FO) are used to develop a sensitive aptasensor with the detection of thrombin as a model. After GO is attached on glass carbon or gold electrodes through physical adsorption, the amino-tagged aptamer is immobilized on the electrode surface via an amide linkage between the amino group at the end of aptamer and the carboxyl groups on GO. The FO is designed to contain two parts: the complementary strand and an intermolecular duplex for the intercalation of Ru(phen)(3)(2+) as ECL probe. The hybridization between aptamer and its complementary part at FO achieves the introduction of Ru(phen)(3)(2+) probe onto the electrode surface for high ECL emission. The hybrid between aptamer and thrombin leads to the release of FO containing the intercalated Ru(phen)(3)(2+) probe. Correspondingly, the decreased ECL emission is used to quantify thrombin. The concentration-dependent response of thrombin is observed between 0.90 pM and 226 pM with a detection limit of 0.40 pM. While GO is used to immobilize the aptamer with various electrodes, such as glass carbon electrode and gold electrode in this work, GO can also preconcentrate TPrA on its surface to improve the sensitivity. The well-designed label-free ECL aptasensor strategy can be easily extended to other targets via the selection of their aptamers. (C) 2013 Elsevier B.V. All rights reserved.