Electroactive Cu2O nanoparticles and Ag nanoparticles driven ratiometric electrochemical aptasensor for prostate specific antigen detection

Early detection of prostate specific antigen (PSA) could reduce the mortality from prostate cancer. Electroactive nanostructures have attracted much attention due to their excellent electronic conductivity and favorable biological microenvironment. In particular, electroactive Cu2O nanoparticles (NPs) and Ag NPs exhibited unique oxidation signals at around -0.1 V and +0.2 V. The separated and non-interfere oxidation signals enabled them to be alternative electrochemical beacons for the establishment of ratiometric electrochemical sensor for PSA detection. Electroactive Cu2O NPs were designed to grow on the surface of reduced graphene oxide/Fe3O4 nanosheets (rGO/Fe3O4 NSs) and served as reference tags due to the stable differential pulse voltammetry (DPV) signals of Cu2O NPs, magnetic properties for the absorption on electrode and the accelerated electron transfer ability of rGO. In order to improve the sensitivity of detection, a large number of small electroactive Ag nanodots were dispersed on the surface of Ag@resorcinol-formaldehyde (RF) NPs and served as detection tags. Electroactive Ag@RF-Ag NPs were assembled with rGO/Fe3O4/Cu2O NSs for the fabrication of ratiometric electrochemical aptasensor. With the addition of PSA, aptamers modified Ag@RF-Ag NPs disassembled from electrode surface, resulting in the decrease of DPV signals near +0.2 V and unchanged DPV signals at -0.1 V. This developed ratiometric electrochemical aptasensor achieved sensitive and accurate PSA detection. This proposed ratiometric electrochemical aptasensor has the advantages of easy preparation, simple structure and wide detection ranges.