A novel electrochemiluminescent immunosensor based on the quenching effect of aminated graphene on nitrogen-doped carbon quantum dots

• ECL behavior of N-CQDs was investigated.
• NH2-G for quenching N-CQDs emission was investigated.
• The linearly range of the immunosensor for AFP was 0.01 ng/mL–100 ng/mL.

Nitrogen-doped carbon quantum dots (N-CQDs) with an average diameter of 2 nm were synthesized by carbonization of diethylene triamine pentacetate acid (DTPA). The simple prepared N-CQDs showed excellent electrochemiluminescence (ECL) property and were used as luminophors to fabricate a sandwich-type ECL immunosensor. Aminated graphene (NH2-G) was also synthesized and used as a label of secondary antibody. The labeled NH2-G could effectively quench the ECL of N-CQDs modified on electrodes due to ECL resonance energy transfer (ERET). Immunological recognition which induced ECL quenching enabled the quantitative determination of biomarkers. Alpha fetoprotein (AFP) was selected as a model analyte to investigate the analytical performance of the proposed immunosensor. Under optimal conditions, a good linear relationship between ECL intensity and the logarithm of AFP concentration was obtained in the range of 0.01–100 ng mL−1 with the detection limit of 3.3 pg mL−1. The proposed ECL immunosensor showed good stability, acceptable selectivity and reproducibility.

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