Simple and signal-off electrochemiluminescence immunosensor for alpha fetoprotein based on gold nanoparticle-modified graphite-like carbon nitride nanosheet nanohybrids

Abstract

A simple, signal-off electrochemiluminescence (ECL) immunosensor for sensitive and selective detection of alpha fetoprotein (AFP) was developed based on gold nanoparticle (AuNPs) modified graphite-like carbon nitride nanosheet (g-C₃N₄ NSs) nanohybrids (Au-g-C₃N₄ NHs). Compared to the g-C₃N₄ NS modified glassy carbon electrode (GCE), the ECL intensity is more obvious at the Au-g-C₃N₄ NH modified GCE due to the fact that AuNPs can promote electron transfer and electrocatalytic reduction of S₂O₈²⁻ to produce large amounts of hole donor (SO₄˙⁻). Results demonstrated that the ECL signal of the g-C₃N₄ NSs decreased due to the interaction between antibody and antigen on the modified electrode. Thus, an ECL immunosensor for the detection of AFP was realized by monitoring the ECL intensity change of g-C₃N₄ NSs. The factors influencing the performance of the immunosensor were investigated in detail. Under optimal conditions, the proposed biosensor achieved a wide line from 0.001 to 5.0 ng mL⁻¹ with a detection limit of 0.0005 ng mL⁻¹. Furthermore, the ECL immunosensor was successfully applied to the determination of AFP in serum samples, providing a promising effective strategy for AFP detection.