Design of organic/inorganic nanocomposites for ultrasensitive electrochemical detection of a cancer biomarker protein.

A new type of nanocomposite composed of carboxylated single-walled carbon nanotubes (CNTs-COOH), reduced graphene oxide (rGO), bovine serum albumin-Ag hybride (Ag@BSA), and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated to develop an ultrasensitive electrochemical platform for the detection of carcinoembryonic antigen (CEA) as a model of biomarkers. Two steps are involved for the fabrication of the organic/inorganic nanocomposites. The Ag@BSA nanoflowers were first synthesized to be doped with CNTs-COOH and rGO followed by the adsorption of PEDOT resulting in CNTs-COOH/rGO/Ag@BSA/PEDOT. The as-prepared nanocomposites were then deposited onto an Au electrode together with subsequent immobilization of CEA antibody (anti-CEA) to construct the electrochemical immunosensor. This unique structure and composition of the developed immunosensor can expect an excellent electrochemical response. The immunosensor offers a linear relationship between the electrochemical responses and the CEA concentrations from 0.002 to 50 ng∙mL with a detection limit of 1 × 10 ng∙mL. Moreover, the ultrasensitive immunoassay can detect CEA in real human serum samples, and the results are comparable to those obtained from the commercial ELISA. Therefore, this strategy can monitor diseases, offer clinical diagnosis, and may be valuable for the development of new biomedical devices.