Electrochemical immunosensor for ochratoxin A detection based on Au octahedron plasmonic colloidosomes

The accurate and rapid fungaltoxin detection at early stage can prevent people from getting cancer to a great extent. Here, an ultrasensitive electrochemical immunosensor for the detection of ochratoxin A was reported. Octahedral gold nanoparticles (Oct Au NPs) with edge and sharp corners as substrate materials can connect more primary antibodies and Au octahedron plasmonic colloidosomes (Au Oct PCs) were formed by the natural settlement of the Oct Au NPs in the inverse emulsion system. Au Oct PCs with high specific surface area and good electron transfer ability can hybridize with electron mediator toluidine blue to act as labels to amplify the output signal and ameliorate the stability of the immunosensor. The immunoassay was performed via the square wave voltammetry and showed a strong current response. The proposed immunosensor obtained a wide linear range from 0.1 pg mL^-1 to 10 ng mL^-1 and a low detection limit of 39 fg mL^-1. This new strategy achieved favorable stability, reproducibility and selectivity, which had potential application in real sample analysis.