A novel ratiometric fluorescent sensor for Ag+ based on two fluorophores

Determining Essential Requirements for Fluorophore Selection in Various Fluorescence Applications Taking Advantage of Diverse Structure-Fluorescence Information of Chromone Derivatives

Herein, we report our work exploring the essential requirements for fluorophore selection during the development of various fluorescence applications. We assembled a library of chromone-derived fluorophores with diverse structure-fluorescence properties, which allowed us to choose the fluorophore pairs with similar structures but differing fluorescence properties and compared the performance of the selected fluorophore pairs in three types of commonly used fluorescence applications. We found that the selection standard of a suitable fluorophore is variable depending on the application. (1) In fluorescence imaging, fluorophores with strong and constant fluorescence under various conditions, such as a large pH range, are preferred. Notably, (2) in the detection of bioactive species, fluorophores with relatively lower fluorescence quantum yield favor the detection sensitivity. Furthermore, (3) in enzymatic assays employing fluorescence, the key parameter is the binding affinity between the fluorophore and the enzyme.

A Water-Soluble Fluorescent Probe for the Selective Sensing of Ag+ and its Application in Imaging of Living Cells and Nematodes

In this study, an imidazole-coumarin based fluorescent probe was developed for the selective and sensitive detection of Ag⁺ in aqueous solution. Using a combination of Job plot, NMR titrations, and DFT calculations, the binding properties between Ag⁺ and the probe were deeply investigated, and the results revealed a 1:1 binding stoichiometry between the probe and Ag⁺ with a binding constant of 1.02 × 10⁶ M^-1. The detection limit was found to be 150 nM, which satisfies the requirement for the quantitative detection of Ag⁺ in real water samples. Moreover, the new probe, Ic, was successfully applied to sense Ag⁺ in HeLa and HepG2 cells as well as in C. elegans, indicating that it could be a useful tool for the environmental monitoring of Ag⁺ pollution. These results demonstrated that Ic could serve as a high-efficiency and low-cost fluorescent probe for tracking Ag⁺ in an aquatic environment and biological organisms.