Porous MB@Cd-MOF Obtained by Post-Modification: Self-Calibrated Fluorescent Turn-on Sensor for Highly Sensitive Detection of Carbaryl
Yujuan Zhang, Lingling Gao, Sai Ma, Tuoping Hu
Abstract
Abuse of pesticides has caused great threat to the environment, so it is urgent to find a fast and sensitive method to detect pesticide residues in agricultural products and water. Herein, a 3D Cd-MOF was designed and synthesized by the reaction of 3,5-di(2′,5′-dicarboxylphenyl)pyridine (H4DDPP) and Cd(NO3)2 under solvothermal conditions. Meanwhile, a stable MB@Cd-MOF composite with dual-emitting characteristic was constructed by the in situ encapsulation of methylene blue (MB) into the channel of Cd-MOF. Compared with Cd-MOF, MB@Cd-MOF exhibits sensitive sensing for carbaryl with the detection limit of 6.7 ng·mL–1 and high accuracy, which are attributed to the fluorescence enhancement effect and dual-emitting characteristics of MB@Cd-MOF. Finally, the fluorescence enhancement mechanisms indicate that the excellent fluorescence properties of MB@Cd-MOF as a self-calibrated sensor are mainly ascribed to energy transfer from carbaryl to MB@Cd-MOF and the photoinduced electron transfer from carbaryl to H4DDPP. At the same time, the relative standard deviation of MB@Cd-MOF for carbaryl in real samples is less than 4.44%, indicating that MB@Cd-MOF has excellent sensing accuracy for carbaryl. Therefore, the rapid fluorescence response and good stability of MB@Cd-MOF endow it with the capacity to sense carbaryl in practical application.