Fluorescent assay for carbendazim determination using aptamer and SYBR Green I

This paper describes a fluorometric assay for the determination of carbendazim (CBZ) in aqueous samples based on an unmodified CBZ-specific aptamer and the fluorescent intercalator SYBR Green I (SG-I). The CBZ aptamer has double-stranded parts and G-quadruplex spatial structures, which can be recognized by SG-I. It leads to strong fluorescent emission of SG-I. In the presence of CBZ, the aptamer will bind to CBZ to form stable compounds due to its specific affinity. This will induce the conformational change of the aptamer. SG-I will then detach from the aptamer, leading to the decrease of its fluorescence. Therefore, the concentration of CBZ is determined through the changes in fluorescence of the system. This fluorometric biosensor for CBZ detection is constructed with a linear range from 3.58 to 230 nM with a limit of detection (LOD) of 3.58 nM. With great sensitivity and selectivity, this assay is efficient and convenient with a < 40 min operation time. Meanwhile, the average recovery of CBZ is 99.87–101.77% in the application of actual water samples with relative standard deviations (RSD) ranging from 1.97 to 2.63%.