Application of nanoporous Pd as catalytically promoted nanolabels for ultrasensitive electrochemiluminescence immunosensor based on Ag/graphene nanocomposite

An ultrasensitive sandwich-type electrochemiluminescence (ECL) immunosensor was designed for carcinoembryonic antigen (CEA) detection. This immunosensor was developed using nanoporous Pd as excellent labels and Ag/graphene (Ag-G) nanocomposite as biosensing substrates. Ag-G nanocomposite was prepared by simultaneous reduction of graphene oxide and Ag ions with a rapid and efficient one-step approach and served as an effective matrix for primary antibodies attachment. The nanoporous Pd obtained from dealloying Pd/Al alloy is an excellent catalyst for the oxidation of H2O2 to generate O-2 due to its large specific surface area and high catalytic activity. O-2 could improve the ECL performance of peroxydisulfate through reducing the strong oxidant SO4 center dot-. The proposed immunosensor successfully fulfilled the ultrasensitive detection of CEA in the range from 1 pg mL(-1) to 500 ng mL(-1) with a detection limit of 0.6 pg mL(-1). Finally, our ECL immunosensor has advantages of high sensitivity, specificity and stability, and could be used to monitor CEA level in human serum with satisfactory results. (C) 2015 Elsevier B.V. All rights reserved.