Electrochemiluminescent resonance energy transfer between amino-modified g-C3N4/Bi2MoO6 composite and carboxyl CoS2 nanoboxes for sensitive detection of alpha fetoprotein

Abstract

This work demonstrates an effective quenching electrochemiluminescent (ECL) immunosensor based on resonance energy transfer for the sensitive detection of alpha fetoprotein (AFP). In this strategy, graphitic carbon nitride (g-C₃N₄) was coupled with bismuth molybdenum oxide (Bi₂MoO₆) to form a g-C₃N₄/Bi₂MoO₆ nanocomposite as a novel type of ECL immunosensor. The as-synthesized amino-modified g-C₃N₄/Bi₂MoO₆ nanocomposite presents strong and stable cathodic ECL activity compared to pristine g-C₃N₄. One plausible reason is that the synergistic effect between the g-C₃N₄ and Bi₂MoO₆ could facilitate charge transfer process and thereby enhancing the separation efficiency of electron-hole pairs. The other functional part of the immunosensor, carboxyl CoS₂ nanoboxes with a broad absorption range, was rationally designed and introduced. The evidence that the absorption spectra of carboxyl CoS₂ NBs overlap with ECL spectra of g-C₃N₄/Bi₂MoO₆ nanocomposite holds accountable for exceptionally weakened ECL signal. This sandwich-type immunosensor was setup based on quenching mechanism concerning amino-modified g-C₃N₄/Bi₂MoO₆ as an ECL donor and carboxyl CoS₂ NBs as an ECL accepter. The strategy was optimized to achieve a convincible and sensitive detection goal for AFP with a wide quantifiable range of 0.5 pg/mL-10 ng/mL whilst a sufficiently low detection limit of 0.04 pg/mL (S/N = 3). This immunosensor shows great potential for real sample analysis with reasonable recoveries ranging from 95.5 to 99.0 %, demonstrating its high precision for AFP determination.

Keywords: Alpha fetoprotein; Electrochemiluminescence; Immunosensor; Nanocomposite; Resonance energy transfer.