Sensitive fluorescent detection of carbamate pesticides represented by methomyl based on the inner filter effect of Au nanoparticles on the fluorescence of CdTe quantum dots

Abstract

Based on the inner filter effect (IFE) of Au nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs), a novel fluorescence method for the rapid assay of carbamate pesticides has been developed. The fluorescence of CdTe QDs was remarkably quenched in the presence of AuNPs via IFE. Acetylcholinesterase (AChE) catalyzed the hydrolysis of acetylthiocholine into thiocholine, which could induce the aggregation of AuNPs and decrease their characteristic absorption, thereby recovering the IFE-decreased fluorescence of the CdTe QDs. Carbamate pesticides can inhibit the activity of AChE, thus preventing the aggregation of AuNPs and the fluorescence recovery of CdTe QDs. Therefore, the IFE of the fluorescence between AuNPs and CdTe QDs could convert the absorption signal to a fluorescence signal, which improved the detection sensitivity of carbamate pesticides in vegetables. The calibration curve for methomyl was established in the range of 0.017–0.5 μg mL⁻¹ with a detection limit of 0.011 μg mL⁻¹ (S/N = 3) which is superior to the HPLC coupled with UV detection method. This method was successfully carried out for the assessment of methomyl in vegetables, and has many advantages such as high sensitivity, low cost and rapidity in comparison with traditional methods.