Gold nanoparticle as an electrochemical label for inherently crosstalk-free multiplexed immunoassay on a disposable chip.

This work proposed a simple, sensitive and low-cost multiplexed immunoassay by combining a disposable chip with gold nanoparticle (AuNP) as an electrochemical label. The immunosensors array as the disposable chip was firstly prepared by immobilizing capture antibodies on different screen printed carbon working electrodes by passive adsorption. With a sandwich mode, the analytes were then bound to the corresponding capture antibodies for further capture of the gold nanoparticle labeled antibodies. Gold nanoparticles were finally electrooxidized in 0.1 M HCl to produce AuCl(4)(-) for differential pulse voltammetric detection. Using human IgG and goat IgG as model targets, under optimal conditions this method achieved linear ranges from 5.0 to 500 and 5.0 to 400 ng mL(-1) with limits of detection of 1.1 and 1.6 ng mL(-1), respectively. This method eliminated completely electrochemical crosstalk between adjacent immunosensors due to the strong adsorption of the AuCl(4)(-) on the printed carbon surfaces. The immunosensors array showed acceptable precision, reproducibility and stability, and could be readily applied to multianalyte determination for clinical diagnostics. 2010 Elsevier B.V. All rights reserved.