Ultrahighly Sensitive Sandwich-Type Electrochemical Immunosensor for Selective Detection of Tumor Biomarkers.

Herein, a novel sandwich-type immunosensor was designed using Pt nanoparticle-decorated SnS nanoplates (Pt@SnS) as a matrix and N,B-doped Eu MOF (N,B-Eu MOF) nanospheres as a signal amplifier. In Pt@SnS, Pt nanoparticles (NPs) enhance the surface electron transport capability and electrochemiluminescence (ECL) performance of SnS nanoplates. The dual "antenna" effect of 5-boronoisophthalic acid (5-bop) and 5-nitroisophthalic acid (5-nop) enables the N,B-Eu MOFs to show very good ECL performance at the cathode. In the presence of the target carcinoembryonic antigen (CEA), the sandwich-type immunosensor provides specific immune responses, and the ECL signal of the immunosensor is greatly amplified by the signal probe N,B-Eu MOFs. In view of the above, the immunosensor was successfully applied for highly sensitive and selective detection of CEA with a detection limit of 0.06 pg·mL. This sensor exhibits high sensitivity and specificity, excellent stability, good reproducibility, and good practicability in real human serum.