Impedimetric detection of trinitrotoluene by using a glassy carbon electrode modified with a gold nanoparticle@fullerene composite and an aptamer-imprinted polydopamine

Abstract

This study introduces a method based on a combination of aptasensing and molecular imprinting for highly sensitive detection of 2,4,6-trinitrotoluene (TNT). An amino-aptamer with inherent affinity for TNT was mixed with TNT prior to covalent attachement onto a glassy carbon electrode surface which was modified with a nanocomposite of the type gold nanoparticle@fullerene (AuNP@C60). Electropolymerization of dopamine around the aptamer/TNT complex entraps the complex and retains the aptamer. After removal of TNT, it is assumed that the MIP cavity acts synergistically with the embedded aptamer to form a nanohybrid receptor (aptamer-molecular imprinting polymer). This results in recognition properties superior to that of aptamer alone. Benefiting from the double specific molecular recognition property of molecular imprinting polymers and aptamers along with the in situ generation of AuNP onto the surface of the modified GCE leads to superb sensing properties. Properties such as lower limit of detection (3.5 attomolar) and wider linear concentration range of TNT (0.01 femtomolar to 1.5 μmol L−1) are distinctly better than other reported methods. In our perception, this strategy may be extended to various diagnostically relevent proteins using not only aptamers but also other affinity molecules such as affimers, antibody and peptide fragments.