A novel electrochemical labeled immunosensor for the detection of gliadin based on graphene oxide and silver nanoparticles

In this study, a labeled electrochemical immunosensor was developed to determine gliadin protein. Herein, the glassy carbon electrode (GCE) surface was modified by the graphene oxide (GO) dispersion followed by electrochemical deposition of silver nanoparticles (AgNPs). Anti-gliadin antibody (Gli-Ab1) was immobilized on this electrode (GCE/GO/AgNPs); subsequently, this platform was incubated with bovine serum albumin (BSA) to prevent non-specific interactions. Gliadin antigen (Gli) followed by horseradish peroxidase-labeled secondary antibody (HRP−Ab2) solutions were added to the GCE/GO/AgNPs/Gli-Ab1/BSA immunosensor surface. Scanning Electron Microscope (SEM) was utilized to investigate the surface properties of the prepared electrodes, and cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) techniques were utilized to investigate their electrochemical properties. The experimental conditions have been optimized to form the appropriate immunosensor structure. The gliadin antigen was determined using DPV after the HRP enzyme substrates (hydroquinone and hydrogen peroxide) were added to the electrochemical cell. The gliadin protein′s linear working range was 0.5–200 μg mL⁻¹. The subjected immunosensor displayed convenient reproducibility and selectivity to the possible interfering substances.