Electrochemical immunosensor based on phages/CdSe nanoparticles as tracers to quantify clomazone in water

Abstract

Clomazone, an herbicide used worldwide, contaminates river and lakes, as well as surface and ground water. Therefore, there is great interest in developing new analytical tools for detecting environmental pollutants that are simple, highly sensitive and provide an extended analytical range. This work describes a disposable, highly sensitive and reproducible electrochemical immunosensor based on a non-competitive and enzyme-free immunoassay to quantify clomazone in water samples. A specific clone of recombinant phage particles labelled with CdSe nanoparticles, which form a trivalent complex with the clomazone/monoclonal antibody anti clomazone immuno-complex, was used as tracer. Clomazone was determined indirectly by square wave anodic stripping voltammetry through the anodic oxidation of Cd previously deposited in an accumulation step from the reduction of Cd2+ ions released from CdSe nanoparticles. An excellent analytical performance, with a limit of detection and a midpoint sensitivity of 0.038 ng mL− 1 and 1.34 ng mL− 1, respectively, were found. The limit of detection was 60-fold lower than the limit of detection obtained using the same antibody and un-label phage in an optimized non-competitive ELISA. The developed electrochemical immunosensor was successively used to assay undiluted river water samples, where very good recoveries percentages were reached. The very low limit of detection achieved with the electrochemical immunosensor allows it to be used as an important environmental tool for the determination of clomazone.