Ultrasensitive detection of ochratoxin A based on biomimetic nanochannel and catalytic hairpin assembly signal amplification

In this paper, an ultrasensitive nanochannel sensor has been proposed for label-free Ochratoxin A (OTA) assay in combination with graphene oxide (GO) and catalyzed hairpin assembly (CHA). The high-performance sensor is segmented into two parts. One is composed of graphene oxide (GO) and DNA probes . In the presence of target OTA, OTA works as a catalyst to trigger the self-assembly pathway of the two probes and initiate the cycling of CHA circuits, which results in numerous double-stranded DNAs (dsDNA) in solution. The excess ssDNA probes are removed by GO. The other part is composed of biomimetic nanochannel coated with polyethyleneimine (PEI) and Zr 4+ , which can quantify the concentration of OTA by detecting the dsDNA in solution. The nanofluidic device has a detection limit of as low as 6.2 pM with an excellent selectivity . The nanochannel based assay was used to analyse food samples (red wine) with satisfied results. Thus, the proposed analytical method will provide a new approach the detection of OTA and can be applied for quality control to ensure food safety.