Ratio fluorescence sensor based on CD/Cu-MOFs for detection of Hg²⁺

Abstract

Trace detection of toxic heavy metals is a very important and difficult problem in several areas: convenience, sensitivity, and reliability. Herein, we develop an innovative fluorescence resonance energy transfer (FRET)-based ratio fluorescence sensor for the detection of heavy metal mercury ion ( H g 2 + ). The sensing platform is composed of coumarin derivatives (CDs) and a copper metal-organic framework (Cu-MOF) named CD/Cu-MOF. The constructed CD/Cu-MOFs ratio fluorescence sensor exhibits dual emission peaks at 430 and 505 nm under the single excitation wavelength of 330 nm. With the addition of H g 2 + , the fluorescence intensity of the system at 430 nm gradually increased, and the fluorescence intensity at 505 nm remained stable, resulting in a change in the fluorescence ratio. There is a good logarithmic relationship between the H g 2 + concentration in the range from 2 × 10 − 8 to 0.001 nM and the ratio of the fluorescence emission intensity of the system ( F 430 / F 505 ) ( R 2 = 0.9901 ), and its calculated detection limit is 3.76 × 10 − 9 n M . In addition, the CD/Cu-MOFs ratio fluorescence sensor has achieved a good recovery rate of standard addition in the actual food sample recovery experiment, which provides an effective method for the detection of H g 2 + in food samples.