An enzyme-free DNA circuit-assisted MoS₂ nanosheet enhanced fluorescence assay for label-free DNA detection

A fluorescence strategy for highly sensitive and selective detection of H5N1 DNA was proposed based on MoS₂ nanosheets and catalytic hairpin assembly. This platform not only avoided any labeling but also reduced the background signal. In the absence of target, CHA could not be triggered and the thiazole orange and MBs complexes were adsorbed on the surface of MoS₂ to quench the fluorescence of TO, resulting in low background signal. However, upon addition of target DNA, the CHA was initiated and produced plenty of MBs duplex which could be far away from the surface of MoS₂ and bind to TO to enhance its fluorescence. This approach exhibited excellent sensitivity and specificity for H5N1 DNA with a detection limit of 7.5 pM, and realized the assay of H5N1 DNA in human serum samples. Furthermore, this platform could be expanded to detect other virus DNA by changing the corresponding molecular beacons, holding the potential of clinical application.