Ultrasensitive electrochemical immunoassay based on graphene oxide–Ag composites for rapid determination of clenbuterol

Abstract

We report the development of an ultrasensitive amperometric biosensor based on Ag nanoparticles-decorated graphene oxide nanosheets (GO) (Ag–GO) for the rapid detection of clenbuterol (CLB). The morphology and structure of the Ag–GO labeled CLB (Ag–GO–CLB) were characterized by transmission electron microscope (TEM), atomic force microscope (AFM), and ultraviolet-visible spectroscope (UV-vis). The immunosensor was prepared by covalently immobilizing capture antibodies on a multi-walled carbon nanotubes-modified glassy carbon electrode. Through competitive immunoreactions, the Ag–GO–CLB nanocomposites were captured on the immunosensor and the silver was measured by positive differential pulse voltammetry (DPV) in KCl solution for the detection of antigen. The experimental results show a linear response over the range from 0.01 to 10.0 ng mL⁻¹ with a lower detection limit of 6.8 pg mL⁻¹ (signal-to-noise ratio of 3). The Ag–GO based immunosensor offers a simple and convenient route for metal-immunoassay labels, which can avoid the complicated and time-consuming dissolving of metal component for ultrasensitive determination. Moreover, the electrochemical immunoassay shows acceptable specificity and stability and is suitable for the determination of CLB in real samples.