Simple and sensitive detection method for diprophylline using glutathione-capped CdTe quantum dots as fluorescence probes

A simple and sensitive method for detecting diprophylline (DPP) was developed based on the fluorescence quenching of glutathione-capped CdTe quantum dots (GSH-CdTe QDs) by using diprophylline in a KH2PO4-Na2HPO4 medium. Parameters affecting the quenching efficiency, including types and pH of buffer solutions as well as temperature, reaction time, adding sequence, and interfering substances, were investigated and optimized. In optimum conditions, the calibration plot of the quenched fluorescence intensity F0/F with a DPP concentration range of 1.67×10-6 mol L−1 to 1.33×10-5 mol L−1 was linear. The detection limit (with signal to noise ratio of 3) for DPP was 2.24×10-7 mol L−1. The proposed method was successfully applied for detecting DPP in human serum. The recovery of the method was in the range of 87.41% to 117.94%. Finally, the possible quenching mechanism of GSH-CdTe QDs and DPP was also discussed.