A novel label-free impedimetric immunosensor for detection of semicarbazide residue based on gold nanoparticles-functional chitosan composite membrane

l-Cysteine (Cys) and chitosan (Chi) were cross-linked to form the functional polymer composite with active groups of thiol and amino groups (denoted as Chi-Cys) under the coupling reagents of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydrosuccinimide (EDC/NHS). Then it was modified on the surface of glassy carbon electrode (GCE). The active groups in Chi-Cys composite can adsorb gold nanoparticles by self-assembly technique. The electrochemical immunosensor can be fabricated by using gold nanoparticles-functional chitosan biological composite film as matrix to immobilize the monoclonal antibody against semicarbazide (SEM) (SEM-McAb). The detection of SEM residue was performed with the technique of electrochemical impedance spectroscopy. Under the optimized conditions, the relative change in impedance was proportional to the logarithmic value of SEM concentrations in the range of 1.0-1.0 × 104 ng mL−1 (r = 0.9998) with the detection limit of 1.0 ng mL−1. The specificity, reproducibility, stability, and accuracy of the proposed impedimetric immunosensor were also evaluated. The proposed immunosensor showed economical, efficient, and potential application for the detection of SEM in food samples.