Electrochemiluminescence immunosensor for the determination of ag alpha fetoprotein based on energy scavenging of quantum dots

An electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of alpha fetoprotein (AFP) was fabricated using graphene-CdS quantum dots-alginate (G-CdS QDs-AL) as the immobilizing support and CdSe/ZnS QDs as the label. CdSe/ZnS QDs could effectively scavenge the ECL of G-CdS QDs-AL composite, and the quenched ECL intensity depended linearly on the logarithm for AFP concentration in the range from 0.05 to 500 fg/mL. The detection limit was 20 ag/mL. The proposed ECL immunoassay protocol for AFP detection is stable, specific, highly sensitive and promising for clinical application.

► LOD for AFP was about 20 ag/mL, 50 times better than the best previously reported. ► Black body-like QDs labeled on second antibody open a new avenue in ultrasensitive ECL bioassays for tumor markers. ► G-CdS QDs-AL composite film is promising in developing an ECL immunosensor.