Electrochemical immunosensor for the detection of interleukin-17 based on Cd2+ incorporated polystyrene spheres

Sensitive electrochemical immunosensor for the detection of interleukin-17 (IL-17) was prepared using cadmium (Cd2+) ion incorporated polystyrene sphere (PS, PS–Cd2+) as label. With the linking of the detection anti-IL-17 antibody (Ab2) onto PS (PS–Cd2+–Ab2), the modified PS can be captured onto the electrode surface through immuno-reaction. Tetrahydrofuran (THF) was then dropped onto the electrode surface to dissolve the PS and release the contained Cd2+ ions onto electrode surface for the following stripping voltammetric detection. Compared to the electrochemical label based on quantum dots (QD), this method for the detection of Cd2+ ion is much simpler and straightforward. With the immobilization of primary anti-IL-17 antibody (Ab1) onto graphene surface, the resulting immunosensor displays high sensitivity, which can be ascribed to the significant number of Cd2+ ions incorporated into PS and a large number of Ab2 linked onto PS surface. The response current was linear to the logarithm of IL-17 concentration in the range from 0.1 pg to 1 ng/mL with a detection limit of 50 fg/mL. The immunosensor results were validated through the detection of IL-17 in serum samples with satisfactory results.