A ratiometric lanthanide fluorescent probe for highly sensitive detection of alkaline phosphatase and arsenate

Abstract A novel dual-ligand lanthanide coordination polymer nanoparticles (ThT@luminol-Eu-GMP CPNPs) were synthesized for detecting alkaline phosphatase (ALP) and arsenate. The ThT@luminol-Eu-GMP CPNPs were constructed through self-assemble of central ion (Eu3+) with bridging ligands of guanosine phosphate (GMP) and luminol, and simultaneously embedded the guest dye molecule thioflavin T (ThT) during the process. This design boosted the fluorescent performance of ThT through two paths. The molecular rotation of ThT was restricted due to the tight embedding of ThT in CPNPs, resulting in an increased fluorescence of ThT on one hand. On the other hand, the overlapped spectra between the emission spectra of luminol and the absorption spectra of ThT induced the FRET effect, which further facilitated the fluorescence of ThT. In the presence of ALP, the ingenious structure of ThT@luminol-Eu-GMP was destroyed due to the specific shear of ALP to GMP, which not only got rid of the limiting effect of ThT, but also broken the FRET between luminol and ThT, leading to a sharply decreased fluorescence of ThT. Meanwhile, the AIE effect of the luminol was promoted, leading to an increased fluorescence of luminol. According to ratio of the fluorescence of luminol to ThT, ALP can be monitored sensitively. Moreover, the ThT@luminol-Eu-GMP can also be used to sensitively detect arsenate based on the inhibition of arsenate for ALP.