Electrochemical stripping voltammetry of gold ions for development of ultra-sensitive immunoassay for chlorsulfuron

The paper reports a highly sensitive enzyme free electrochemical immunoassay (EFEIA) for the detection of herbicide chlorsulfuron. The assay is based upon oxidative gold nanoparticle (GNP) dissolution in an acidic solution. The consequent release of large amounts of gold (Au) metal ions after dissolution of gold nanoparticles tagged to antibody leads to the development of sensitive stripping voltammetry based immunoassay. The detection is made possible by the reduction of Au3 + ions at the screen printed electrode surface followed by metal analysis by using the square wave voltammetry technique. The sensitivity of chlorsulfuron detection by competitive assay procedure was 6.7 pg mL− 1 for EFEIA in marked contrast to optical detection using Standard ELISA procedure that gives a sensitivity of 4.97 ng mL− 1.

An enzyme free electrochemical immunoassay (EFEIA) for the detection of herbicide chlorsulfuron has been presented. The assay in a competitive inhibition immunoassay format demonstrates the competition between free antigen (chlorsulfuron) and hapten–protein conjugate for the available binding sites of antibody–GNP complex. The gold nanoparticles after acidic dissolution release large amounts of gold (Au) metal ions which were subsequently detected by stripping voltammetry technique using a screen printed electrode.Figure optionsDownload as PowerPoint slideHighlights
► Ultra sensitive immunoassay for detection of herbicide chlorsulfuron.
► Enzyme Free Electrochemical Immunoassay (EFEIA) based on Gold nanoparticles.
► Stripping voltammetry of large amount of gold ions released on GNP dissolution.
► High sensitivity for EFEIA (EC50~ 6.7 pg mL–1) than ELISA (EC50~ 4.97 ng mL–1).