An amplified AuNP-mediated chemiluminescence resonance energy transfer aptasensor based on Nb.BbvCI-powered DNA walker for detecting ochratoxin A in foods

The application of the fluorescence resonance energy transfer (FRET) strategy in the detection of ochratoxin A (OTA) is restricted by factors such as the photobleaching of fluorescent dyes, the autofluorescence of ochratoxin A (OTA), and the necessity for excitation by an external light source. The chemiluminescence resonance energy transfer (CRET) technique provides a more effective solution to this issue. In this paper, we developed a novel CRET aptasensor, based on gold nanoparticle (AuNP)-mediated CRET and Nb.BbvCI-powered DNA walker signal amplification. In the AuNPs/Capture-DNA/HRP probe, horseradish peroxidase (HRP) approached the AuNP surface, resulting in CRET. AuNPs quenched the chemiluminescence generated by HRP-catalyzed luminol. The presence of OTA induced the separation of the Walk-DNA from the aptamer and the formation of a double strand with Capture-DNA. This activated Nb.BbvCI to cleave Capture-DNA, releasing HRP and Walk-DNA. The Walk-DNA acted as a DNA walker, moving toward the adjacent Capture-DNA and initiating the next cleavage by Nb.BbvCI. Ultimately, a significant amount of HRP was released from the AuNP surface, weakening the CRET effect while generating a strong chemiluminescent signal. The CRET aptasensor had a detection limit of 2.75 nM with a linear range of 5–40 nM and was applied to detect OTA in glutinous rice.