Enhancement of the sensing performance and stability of a MOF based-molecularly imprinted polymer by utilizing dual-ligands and triethanolamine catalysis

Abstract

In this work, a terbium MOF-based molecularly imprinted polymer (Tb-MOF@SiO2@MIP) was prepared using two ligands as organic linkers and triethanolamine (TEA) as a catalyst to improve the sensing performance and stability of the fluorescence sensors. The obtained Tb-MOF@SiO2@MIP was then characterized using a transmission electron microscope (TEM), energy dispersive spectroscopy (EDS) Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The results revealed that Tb-MOF@SiO2@MIP was successfully synthesized with a thin imprinted layer of 76nm. The synthesized Tb-MOF@SiO2@MIP maintained 96% of its original fluorescence intensity after 44 days in aqueous environments because of appropriate coordination models between the imidazole ligands as a nitrogen donor and Tb (Ⅲ). Furthermore, TGA analysis results indicated that an increase in the thermal stability of Tb-MOF@SiO2@MIP was attributed to the thermal barrier from a MIP layer. The Tb-MOF@SiO2@MIP sensor responded well to the addition of imidacloprid (IDP) in the range of 2.07-150ngmL-1 with a low detection limit of 0.67ngmL-1. In vegetable samples, the sensor can quickly detect IDP levels with the average recovery ranging from 85.10 to 99.85% and RSD values ranging from 0.59 to 5.82%. The UV-vis absorption spectrum and density functional theory analysis results revealed that the inner filter effect and dynamic quenching process both contributed to the sensing process of Tb-MOF@SiO2@MIP.