Enhanced Electrochemical And Sers Signals By Self-Assembled Gold Microelectrode Arrays: A Dual Readout Platform For Multiplex Immumoassay Of Tumor Biomarkers

In this study, a dual readout biosensor is reported that combines electrochemical and surface-enhanced Raman scattering (SERS) for a multiplexed immunoassay of tumor biomarkers. A gold microelectrode array (GMA) was fabricated by electrodeposition of Au to the bottom of numerous individual silica cavities. Electrochemical studies demonstrate that the GMA possesses unique charge selectivity and an inherently high S/N ratio, which make the GMA especially suitable for differential pulse voltammetry (DPV) and square wave voltammetry (SWV) detection. Hybridization chain reaction (HCR) was designed to increase the load of labelled molecules in this super-sandwich structured biosensor. Meanwhile, the strong plasmon coupling between silver nanoparticles and the underlying gold particles enabled ultrahigh sensitivity of the GMA when using SERS readout. By combining electrochemical and SERS methods, we achieved the high-throughput preliminary screening of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA). Further quantitative analysis showed that the two proteins could be determined in a wide concentration range, and their minimum detection limits were 0.6 and 0.3 pg.mL(-1) when using SERS method, respectively. The applicability of the proposed dual readout platform in clinical diagnosis was verified by the detection in human serum samples.