A Novel Label-Free Impedance Immunosensor Based on Sol-Gel for Determination of Carbofuran

In this study, a novel label-free impedance immunosensor for the direct detection of carbofuran was developed using silica sol gel (SiSG) as as immobilizing agent. The anti-carbofuran monoclonal antibody was immobilized onto the surface of the glassy carbon electrode (GCE) in aperture of SiSG. The conformational properties of the immunosensor and electrochemical performance of immunoreaction between carbofuran and the anti-carbofuran monoclonal antibody were characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Effects of experimental variables, such as concentration of antibody solution, pH of working buffer, the pH of the anti-carbofuran incubating solution and incubation time were studied in detail for optimization of analytical performance. Under optimal conditions, the linear range of the proposed immunosensor for the determination of carbofuran was from 1 ng/mL to 100 mu g/mL and 50 mu g/mL to 200 mu g/mL with correlation coefficients of 0.9928 and 0.9914, respectively. The detection limit was 0.3 ng/mL. The proposed immunosenor exhibited good precision, acceptable stability and reproducibility and could be used for the detection carbofuran pesticide, which provided a potential alternative tool for thedetection of trace amounts of chemical residues in food samples.