A novel amperometric immunosensor based on Fe3O4 magnetic nanoparticles/chitosan composite film for determination of ferritin.

A novel amperometric immunosensor was developed by immobilizing ferritin antibody (FeAb) on the surface of Fe(3)O(4) magnetic nanoparticles/chitosan composite film modified glassy carbon electrode (GCE). This material combined the advantages of inorganic Fe(3)O(4) nanoparticles with the organic polymer chitosan. The stepwise assembly procedure of the immunosensor was characterized by means of differential pulse voltammetry (DPV) and ac impedance. The K(3)Fe(CN)(6)/K(4)Fe(CN)(6) was used as a marker to probe the interface and to determinate ferritin. The factors that could influence the performance of the resulting immunosensor were studied in detail. After the immunosensor was incubated with ferritin for 32 min at 35 degrees C, the DPV current decreased linearly with the logarithm of ferritin concentration in the range from 20 to 500 ng mL(-1) with a correlation coefficient of 0.995 and a detection limit of 7.0 ng mL(-1). This immunosensor was used to analyze ferritin in human serum samples. The analytical results showed that the developed immunoassay was comparable with the radioimmunoassay (RIA), and the studied immunosensor exhibited good accuracy, high sensitivity, and long-term stability for 3 weeks, which implies a promising alternative approach for detecting ferritin in clinical diagnosis.