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

- A new cascade reaction signal-amplified strategy was introduced in a label-free amperometric immunosensing platform.
- The multifunctional conductive hydrogel can be synthesised by one-pot method and exhibited good conductivity and large specific surface area.
- The immunosensor exhibited an ultralow detection limit of 0.65 pg mL−1.

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 (S/N = 3). The presented method was further used for the analysis of human serum samples and showed good consistency with detection results from an electrochemiluminescence immunoassay.

A cascade reaction signal-amplified strategy was introduced in a label-free amperometric immunosensing platform. The glucose can be oxidised by glucose oxidase to improve the signal. Moreover, the produced H2O2 by the oxidisation of the glucose can also be catalysed by polythionine to further enhance the signal.195