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.