A fluorescence aptamer sensor utilizing WS₂ nanosheets for sensitive detection of patulin: enhanced specificity and...

A tungsten disulfide (WS₂) nanosheet-based aptamer sensor was developed to detect patulin (PAT). The 5'-end of the PAT aptamer was modified with a cyanine 3 (Cy3) fluorophore, which self-assembled on WS₂ nanosheets. The interaction between the Cy3 fluorophore at the 5'-end of the PAT aptamer and the WS₂ nanosheets resulted in reduced fluorescence (FL) intensity due to fluorescence resonance energy transfer (FRET). The introduction of PAT into this sensing system led to hybridization with the PAT aptamer, forming a G-quadruplex/PAT complex with low affinity for the WS₂ nanosheet surface. This hybridization increased the distance between the Cy3 fluorophore and the WS₂ nanosheets, inhibiting FRET and producing a strong FL signal. Under optimal experimental conditions, the FL intensity of the sensing system demonstrated an excellent linear correlation with PAT concentrations ranging from 0.5 to 40.0 ng mL^-1, and it achieved a detection limit (S/N = 3) of 0.23 ng mL^-1. This sensing system offers enhanced specificity for PAT detection and has the potential for broad application in detecting other toxins by substituting the sequence of the recognition aptamer.