Electrochemiluminescence of CdSe quantum dots for highly sensitive competitive immunosensing

A competitive immunosensor using CdSe quantum dots (QDs) as a label was highly proposed for the detection of a tumor marker. CdSe QDs were characterized by transmission electron microscope image, photoluminescence spectra and ultraviolet-visible absorption spectra. The fabrication process of the immunosensor was traced with electrochemical impedance spectra. Using a-fetoprotein (AFP) as a model, a simple electrochemiluminescence immunosensing platform based on CdSe QDs using competitive binding between conjugated antibody-CdSe QDs and free AFP with immobilized AFP on Au electrode was developed. Under the optimum conditions, the proposed electrochemiluminescence method could detect AFP ranging from 0.05 to 100 mu g/L with a detection limit of 0.005 mu g/L. The proposed immunosensor showed good analytical performance and was successfully applied to detecting level of MP in human serum samples, which would provide a new and promising direction for clinical application. (C) 2012 Elsevier B.V. All rights reserved.