Efficient preparation of dual-emission ratiometric fluorescence sensor system based on aptamer-composite and detection of bis(2-ethylhexyl) phthalate in pork.

A ratiometric fluorescence sensor system is proposed for detecting bis(2-ethylhexyl) phthalate (DEHP) in pork, which is based on aptamer recognition with molybdenum disulfide quantum dots and cadmium telluride quantum dots (MoS2 QDs/CdTe-Apta). Two signals exist in the system, among which the response signal is transmitted by CdTe-Apta. The amide condensation between aptamers and CdTe QDs shortens the distance between CdTe QDs and DEHP, thus quenching the fluorescence of CdTe QDs, possibly through a photoinduced electron transfer mechanism. The MoS2 QDs deliver the self-calibration signal, and the fluorescence of MoS2 QDs remains almost constant when co-existing with DEHP. Linearity (R2 = 0.9536) was established for the DEHP concentration range 0.005-3.0 mg·L-1, with a limit of detection of 0.21 μg·L-1. The system was successfully applied in the determination of DEHP in pork. The system has potential for the quantitative determination of DEHP in practical applications.