An electrochemical immunosensor for rapid determination of clenbuterol by using magnetic nanocomposites to modify screen printed carbon electrode based on competitive immunoassay mode

A novel magnetic field controllable and disposable electrochemical immunosensor for rapid determination of clenbuterol (CLB) was fabricated by graphene sheets (GS)-Nafion (Nf) film dropped on the screen-printed carbon electrode (SPCE) and then Fe3O4-Au nanoparticles (GoldMag particles, GMP) coated bovine serum albumin-CLB (BSA-CLB) conjugates were absorbed on it with the aid of external magnetic field. X-ray powder diffractometer (XRD), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were employed to characterize the synthesized GS and the construction processes of the modified electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study its electrochemical properties. The content of CLB was determined with a competitive immunoassay mode. When different concentration of CLB and 2.0 μg/mL anti-CLB were added to the phosphate buffer solution (PBS) containing 2 mmol/L K3[Fe(CN)6], the percentage of anodic peak DPV current increase ratio (CI%) was proportional to the concentration of CLB over the range of 0.5 ng/mL to 200.0 ng/mL after incubation for 15 min at 35 °C. The detection limit was 0.22 ng/mL. The immunosensor was employed to determine CLB in pork samples and the results were consistent with high-performance liquid chromatography (HPLC) method. The proposed electrochemical immunosensor is sensitive, rapid, magnetic field controllable, low sample consumable and disposable, which is suitable for determining trace CLB in real samples.