Ratiometric fluorescence detection of dipicolinic acid based on Microporous Ln/melamine-terephthaladehyde schiff base networks complex.

Lanthanide-based fluorescence sensor in the detection of major Anthrax biomarker dipicolinic acid (DPA) is attracting wide attention. In this work, we proposed a new strategy for ratiometric fluorescence detection of DPA based on microporous Ln/melamine-terephthaladehyde Schiff base networks (Ln/MTSNW) complex for the first time. The microporous MTSNW was prepared by amine-aldehyde condensation between melamine and terephthaladehyde and presented lamellar and octahedral structure. Lanthanide ions, Eu3+ or Tb3+ were coordinated with N atoms of MTSNW to form Ln/MTSNW complex. The microporous Ln/MTSNW complex not only provided large surface area to improve the sensitivity of DPA detection, but also constructed ratiometric fluorescence sensors to eliminate environmental effects and instrument fluctuation. DPA was a highly efficient antenna molecule for Eu3+ and Tb3+ and transferred the energy to Eu3+ or Tb3+ to sensitize their fluorescence. The Ln/MTSNW complex were uniformly and stably dispersed in aqueous solution for DPA detection with a linear range from 15 nM to 7 μM and low detection limit of 5.2 nM for Eu/MTSNW and a linear range from 4 nM to 2.5 μM and low detection limit of 1.4 nM for Tb/MTSNW. Due to the simple preparation of Ln/MTSNW complex and low technical requirement, the ratiometric fluorescence DPA sensor based on Ln/MTSNW complex might show great potential in practical applications.