Electrochemical immunosensor with PVP/WS2 nanosheets electrode for fibroblast growth factor 21 detection based on metal organic framework nanozyme

A novel electrochemical immunosensor with poly(vinyl pyrrolidone)-tungsten disulfide (PVP/WS 2 ) nanosheets electrode was fabricated for fibroblast growth factor 21 (FGF-21) detection based on gold nanoparticles and metal organic framework (AuNPs/MOFs) nanozyme. The PVP/WS 2 nanosheets enabled direct antibody immobilization on the electrode surface and exhibited high conductivity. The MOFs nanozyme peroxidase-like activity efficiently converted a o -phenylenediamine substrate to 2,2-diaminoazobenzene, which generated an ideal electrochemical signal for monitoring FGF-21 concentrations. The electrochemical immunosensor was fully characterized via Impedance spectroscopy (EIS), Cyclic voltammetry (CV), Squarewave voltammetry (SWV), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Ultraviolet-visible spectroscopy (UV–vis). The biosensor exhibited a good linear relationship over the range 1 pg mL −1 to 100 ng mL −1 , and a superior limit of detection (LOD) as low as 0.24 pg mL −1 . It was successfully used to determine FGF-21 concentrations in serum samples and achieved satisfactory results, indicating great potential applications in clinical diagnostics. • Fe-MOF nanozyme as signal probe reduced the cost and widened the reaction conditions. • PVP/WS 2 nanosheets modified electrode improved the conductivity and sensing properties. • The immunosensor exhibited wide dynamic range and excellent sensitivity. • The immunosensor can detect FGF-21 in human serum. • The whole analytical process can be finished in 1 h.