An ultrasensitive electrochemical immunosensor for the detection of human immunoglobulin G based on Ag@BSA microspheres

Abstract

A novel human immunoglobulin G (HIgG) electrochemical immunosensor was developed based on nanosilver-doped bovine serum albumin microspheres (Ag@BSA). The immunosensor was prepared step-wise by first modifying the electrode with β-cyclodextrin functionalized gold nanoparticles followed by the immobilization of captured antibodies and then the formation of a sandwich-type immunocomplex to introduce Ag@BSA bionanoprobes on the sensor surface. The amplification pathway using the stripping voltammetric measurement of silver ions released from Ag@BSA to monitor the immunoreaction was first adopted. The immunosensor exhibited a large dynamic range of 1 fg mL⁻¹ to 10 pg mL⁻¹ and an ultralow detection limit of 0.5 fg mL⁻¹ to HIgG. Moreover, the immunosensor also showed acceptable stability and reproducibility. This biosensor was applied to the detection of the HIgG level in real serum samples.