Switchable fluorescence sensor toward PAT via CA-MWCNTs quenched aptamer-tagged carboxyfluorescein

A quenching based apta-sensing platform was developed for the detection of Patulin. Three different aptamer sequences were studied to screen the aptamer with the maximum affinity towards Patulin. Carboxyfluorescein (CFL) was used as a fluorescent dye while -COOH functionalized multiwall carbon nanotubes (MWCNTs) were applied as novel nanoquenchers. Aptamer tagged at the 3' end with 40 nucleotide bases exhibited the maximum affinity towards Patulin and caused substantial fluorescence recovery. Interestingly, the limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.13 mu g L-1 and 0.41 mu g L-1 respectively. Commonly occurring mycotoxins in food were also tested to confirm the selectivity of apta-assay. The developed apta-assay was applied to a spiked apple juice sample and toxin recoveries were observed ranging from 96% to 98% (n = 3). These results demonstrated the potential of the developed apta-assay for the selective detection and quantification of Patulin in food samples.