Aptasensor based on tripetalous cadmium sulfide-graphene electrochemiluminescence for the detection of carcinoembryonic antigen.

A facile label-free electrochemiluminescence (ECL) aptasensor, based on the ECL of cadmium sulfide-graphene (CdS-GR) nanocomposites with peroxydisulfate as the coreactant, was designed for the detection of carcinoembryonic antigen (CEA). Tripetalous CdS-GR nanocomposites were synthesized through a simple onepot solvothermal method and immobilized on the glassy carbon electrode surface. L-Cystine (L-cys) could largely promote the electron transfer and enhance the ECL intensity. Gold nanoparticles (AuNPs) were assembled onto the L-cys film modified electrode for aptamer immobilization and ECL signal amplification. The aptamer modified with thiol was adsorbed onto the surface of the AuNPs through a Au-S bond. Upon hybridization of the aptamer with the target protein, the sequence could conjugate CEA to form a Y architecture. With CEA as a model analyte, the decreased ECL intensity is proportional to the CEA concentration in the range of 0.01-10.0 ng mL(-1) with a detection limit of 3.8 pg mL(-1) (S/N = 3). The prepared aptasensor was applied to the determination of CEA in human serum samples. The recoveries of CEA in the human serum samples were between 85.0% and 109.5%, and the RSD values were no more than 3.4%.