Biomimetic nanochannels for molybdate transport: application to sensitive electrochemical immunoassay for HER2

A nanochannel-based electrochemical immunoassay was developed for the detection of human epidermal growth factor receptor 2 (HER2), with molybdate as the reporter to explore the interaction occurring into the nanochannels. The presence of target increased steric hindrance of the antibody-functionalized nanochannels, thereby hindering the transport of molybdate. And the reporter could be monitored by working electrode modified with hydroxyapatite nanoparticles, based on the formation of the redox-active molybdophosphate. As a result, peak current obtained at ca. - 0.28 V in square wave voltammograms could be applied to quantitative determination of HER2. The electrochemical signal increased linearly with the logarithm of the concentration of HER2 in a broad dynamic range of 0.1 pg∙mL^-1 to 10 ng∙mL^-1 with a detection limit of 0.05 pg∙mL^-1. The reliability of this immunoassay was validated by a recovery range of 99.5% to 111.7% for the detection of three different levels of HER2 in human serum samples. Integrating with multiple bionanochannels, this immunoassay is expected to provide a versatile approach for quantitative detection of various biomarkers in related disease diagnosis and therapy.