A novel homogeneous label-free aptasensor for 2,4,6-trinitrotoluene detection based on an assembly strategy of electrochemiluminescent graphene oxide with gold nanoparticles and aptamer

We report a novel homogeneous label-free aptasensor for 2,4,6-trinitrotoluene (TNT) detection based on an assembly strategy of electrochemiluminescent graphene oxide (GO) with gold nanoparticles (AuNPs) and aptamer. In this sensing strategy, the anti-TNT aptamer was first assembled with AuNPs to form aptamer-AuNPs. Then ruthenium(II) complex functionalized GO (denoted as Ru-GO) was assembled with aptamer-AuNPs by electrostatic interaction. AuNPs could directly quench the electrochemiluminescence (ECL) emission of ruthenium(II) complex on the surface of Ru-GO due to the energy transfer from luminophore to the AuNPs. Weak ECL signal of the assembly was obtained. In the presence of target molecule TNT, the aptamer-AuNPs would aggregate partly due to the aptamer-target interaction and reduce quenching effect, leading to ECL signal restoration and strong ECL signal was obtained. TNT in a range of 0.01-100 ng mL(-1) could be detected by use of the ECL intensity discrepancy with a low detection limit of 3.6 pg mL(-1). The aptasensor also showed high selectivity towards TNT against 2,4-dinitrotoluene, p-nitrotoluene and nitrobenzene. The present aptasensor has been successfully applied to the detection of TNT in real water samples. Compared with previous reported sensors, this homogenous aptasensor avoided complicated labeling and purification procedure and showed magnificent sensitivity and high selectivity, which made it not only convenient but also time-saving and applicable. Furthermore, this sensing strategy also provides a promising way to develop new ECL aptasensor for other analytes by virtue of other aptamers. (C) 2012 Elsevier B.V. All rights reserved.