A bimetallic (Cu-Co) Prussian Blue analogue loaded with gold nanoparticles for impedimetric aptasensing of ochratoxin a.

Bimetallic (Cu-Co) Prussian Blue analogs (PBAs) were coupled to gold nanoparticles to give a nanocomposite of type AuNP@CuCoPBA. It is shown to be a viable material for the impedimetric aptamer-based determination of ochratoxin A (OTA). Basic characterizations revealed that the chemical composition and crystal structure of AuNP@CuCoPBA is similar to that of pristine CuCo PBA. Nevertheless, the nanocube shape of CoCu PBA is converted to small nanoparticles on addition of AuNPs. Compared with CuCoPBA-based aptasensor, the AuNP@CuCoPBA-based assay exhibits excellent electrochemical conductivity, strong aptamer binding interaction, and high G-quadruplex stability. Electrochemical impedance spectroscopy revealed that the assay has limits of detection as low as 5.2 fg mL-1 of OTA, a response in the 50 fg mL-1 to 10 ng mL-1 concentration range, high selectivity, good reproducibility, repeatability, and acceptable applicability. In our perception, it represents a universal and powerful method for aptamer strand immobilization. It may be applied to the determination of various other analytes for which aptamers are available. Graphical abstract Schematic presentation of the preparation of a novel bimetallic Cu-Co PBAs coupling with gold nanoparticles (AuNPs) was supplied. The AuNP@CuCoPBA composite was applied for the sensitive detection of ochratoxin A (OTA). The impedimetric aptasensensor based on AuNP@CuCoPBA displays extremely low limits of detection toward OTA (5.2 fg mL-1), along with high selectivity, good reproducibility, high stability, repeatability, and acceptable applicability.