Gold-silver nanocomposite-functionalized graphene sensing platform for an electrochemiluminescent immunoassay of a tumor marker

A novel electrochemiluminescence (ECL) immunosensor based on a prepared 3D paper device was designed for the sensitive detection of a tumor marker in human serum by using CdTe quantum dot coated carbon microspheres (QD@CMs) as bionanolabels. To construct such an ECL immunosensor, gold-silver nanocomposite-functionalized graphene was prepared and used as a sensing platform, which increased the surface area to capture a large number of primary antibodies as well as improving the electronic transmission rate. With the employment of the as-prepared QD@CMs as bionanolabels, a good ECL performance (excellent precision and sensitivity) was exhibited through a sandwich-type immunoassay. To examine the signal amplification of the immunoassay, the analytical properties of various immunosensor platforms and labels were compared in detail. As a proof-of-concept, cancer antigen 125 was used as a model analyte and satisfactory results were obtained. Therefore, the proposed method provides a new promising platform for clinical immunoassays of other biomolecules.