Detection of human immunoglobulin G by label-free electrochemical immunoassay modified with ultralong CuS nanowires

Abstract

Ultralong copper sulfide nanowires (CuSNWs) were synthesized via a simple wet chemical route. Due to the desired surface charge characteristics and attractive electrocatalytic activity toward the oxidation of ascorbic acid, such ultralong one-dimensional nanomaterials provided an interesting platform for electrochemical signal amplification. By immobilizing an anti-IgG antibody on the chitosan (CS)–CuSNWs film, a novel label-free electrochemical immunosensor was thus developed for detection of human immunoglobulin G (IgG). Various experimental parameters were studied, and the interference effects from other proteins were checked. Under the optimum conditions, the decrease of the amperometric signal presented a linear relationship in the IgG concentration range of 0.001–320 ng mL⁻¹ with a detection limit of 0.1 pg mL⁻¹ (S/N = 3). The practical application of the fabricated immunosensor has also been demonstrated by detecting IgG in real human serum samples. The satisfactory results hint the significant potential in clinical analysis.