Electrochemical Immunosensor Based on the Chitosan-Magnetic Nanoparticles for Detection of Tetracycline

In this paper, a low-cost, simple, and highly sensitive electrochemical immunosensor was fabricated for the tetracycline detection based on gold electrode-modified carboxyl-Fe3O4 nanoparticle (MNPs) by chitosan (CS) as linker. The anti-tetracycline monoclonal antibody (Ab) was immobilized on the modified electrode surface. The binding of tetracycline to Ab was analyzed by differential pulse voltammetry. Here, MNPs were used as the signal amplifier to improve the sensitivity of the immunosensor. The stepwise assembly process of the electrochemical immunosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimum operating conditions, the fabricated immunosensor showed a linear current response to the target concentration in the range from 0.08 to 1 ng/mL with a lower detection limit of 0.0321 ng/mL (S/N = 3). It was successfully applied to the detection of tetracycline in milk. Enzyme-linked immunoassay analysis was also conducted to detect tetracycline in the same samples for demonstrating the applicability of the electrochemical immunosensor.