Electrochemical immunosensor based on hollow porous Pt skin AgPt alloy/NGR as a dual signal amplification strategy for sensitive detection of Neuron-specific enolase

Neuron-specific enolase (NSE) is a specific marker for small cell carcinoma (SCLC). Sandwich-type electrochemical immunosensors are powerful for biomarker analysis, and the electrocatalytic activity of the signal amplification platform and the performance of the substrate are critical to their sensitivity. In this work, N atom-doped graphene functionalized with hollow porous Pt-skin Ag–Pt alloy (HP–Ag/Pt/NGR) was designed as a dual signal amplifier. The hollow porous Pt skin structure improves the atomic utilization and the larger internal cavity spacing significantly increases the number of electroactive centers, thus exhibiting more extraordinary electrocatalytic activity and durability for H2O2 reduction. Using NGR with good catalytic activity as the support material of HP-Ag/Pt, the double amplification of the current signal is realized. For the substrate, polypyrrole-poly(3,4-ethylenedioxythiophene) (PPy-PEDOT) nanotubes were synthesized by a novel chemical polymerization route, which effectively increased the interfacial electron transfer rate. By coupling Au nanoparticles (Au NPs) with PPy-PEDOT, the immune activity of biomolecules is maintained and the conductivity is further enhanced. Under optimal conditions, the linear range was 50 fg mL−1 - 100 ng mL−1, and the limit of detection (LOD) was 18.5 fg mL−1. The results confirm that the developed immunosensor has great promise for the early clinical diagnosis of SCLC. •HP-Ag/Pt/NGR effectively realizes the double amplification of current signal.•PPy-PEDOT nanotubes were prepared by a simple chemical polymerization method.•Highly sensitive immunoassay interface based on maintaining the physiological activity of biomolecules.•This proposed immunosensor exhibited ultralow detection limit of 18.5 fg mL−1.