Enzyme-less electrochemical displacement heterogeneous immunosensor for diclofenac detection

Publication date: 15 November 2017
Source:Biosensors and Bioelectronics, Volume 97
Author(s): T.T.K. Nguyen, T.T. Vu, G. Anquetin, H.V. Tran, S. Reisberg, V. Noël, G. Mattana, Q.V. Nguyen, Tran Dai Lam, M.C. Pham, B. Piro
We describe an electrochemical immunosensor based on functionalization of a working electrode by electrografting two functional diazonium salts. The first one is a molecular probe, diclofenac, coupled with an arylamine onto which a specific antibody is immobilized by affinity interactions; the second is a redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The steric hindrance induced by the antibody leads to a current decrease upon binding of the antibody on the grafted molecular probe; conversely, when diclofenac is present in solution, a displacement equilibrium occurs between the target diffusing into the solution and the grafted probe. This leads to dissociation of the antibody from the electrode surface, event which is transduced into a current increase ("signal-on" detection). The detection limit is ca. 20 fM, corresponding to 6pgL⁻¹ diclofenac, which is competitive compared to other label-free immunosensors. We demonstrate that the sensor is selective and is able to quantify diclofenac in tap water.

Graphical abstract

http://ift.tt/2s3Oh6v