Enhanced amperometric immunoassay for the prostate specific antigen using Pt-Cu hierarchical trigonal bipyramid nanoframes as a label

A dual enhancing strategy has been employed to develop a sandwich type of electrochemical immunoassay for the prostate specific antigen (PSA). The signal is enhanced by using Pt-Cu hierarchical trigonal bipyramid nanoframes (HTBNFs) and a composite consisting of Fe 3 O 4 nanoparticles and reduced graphene oxide in polydopamine that serve to capture the primary antibody (Ab1). This nanocomposite shows better electrical conductivity than Fe 3 O 4 and reduced graphene oxide (RGO), respectively, alone. The Pt-Cu HTBNFs were used to label the secondary antibody (Ab2) and act as tags for signal amplification by virtue of their outstanding electrochemical reduction activity towards H 2 O 2 . At a working potential of +0.1 V (vs. SCE), the interference by dissolved oxygen can be avoided. This immunoassay is highly sensitive, with a linear range that extends from 0.1 pg⋅mL −1 to 5 ng⋅mL −1 and an ultralow detection limit of 0.03 pg⋅mL −1 . Schematic of the dual amplification strategy in the immunosensor for the prostate specific antigen (PSA) that is based on the use of a first antibody (Ab 1 ) conjugated to a Fe 3 O 4 -reduced graphene oxide nanocomposite (Fe 3 O 4 -RGO), and of Pt-Cu trigonal bipyramid nanoframes as a label for the second antibody (Ab 2 ).