Transmembrane Transport of Fluoride Studied by Time-Resolved Emission Spectroscopy

Anion carriers are developed for their potential biological applications, including antibacterial properties. However, only a few fluoride carriers have been reported and no reliable spectroscopic method exists for the study of fluoride transport in liposomes. Here we present the use of an encapsulated europium(III) complex to monitor fluoride transport. We take advantage of the long emission lifetime of this probe to use time-resolved emission spectroscopy to study fluoride transport by a fluorescent phosphonium borane. Furthermore, the high sensitivity, selectivity, and versatility of the assay allowed us to study different types of fluoride transporters and unravel their mechanisms of action. This revealed the phosphonium borane and the bambusuril to be active as F-/Cl- antiporters, and the antimony-based compound to be a more efficient OH-/Cl- antiporter, while demonstrating the power of lanthanide probes for studying anion transport.