A cascade reaction signal-amplified amperometric immunosensor platform for ultrasensitive detection of tumour marker

A new strategy for signal amplification was introduced in a label-free amperometric immunoassay platform. Improvements in the signal occurred following the oxidation of glucose by glucose oxidase and catalysis by polythionine of the produced H2O2 from the previous oxidation reaction. In addition, a multifunctional conductive hydrogel, polypyrrole-polythionine-gold with glucose oxidase, was synthesised with a one-pot method using pyrrole and thionine as monomers, ammonium persulfate and HAuCl4 as co-oxidant agents, and glucose oxidase as the doping agent. Combined with the hydrogel, a label free amperometric immunoassay for the tumour marker neuron-specific enolase (NSE) was obtained. If operated at 0 V (vs. Ag/AgCl), the sensor exhibited a wide liner range from 100 ng mL(-1) to 1 pg mL(-1) and ultralow detection limit of 0.65 pg mL(-1) (SIN = 3). The presented method was further used for the analysis of human serum samples and showed good consistency with detection results from an electrochemilu-minescence immunoassay. (C) 2017 Elsevier B.V. All rights reserved.