Abstract
A new fluorescent chemosensor for copper (II) and subsequent anion sensing was designed and fully characterized. The sensor consisted of a 1,8-naphthalimide core, bearing two terminal dipicolylamine (DPA) receptor units for binding metal cations, and an ethoxyethanol moiety for enhanced water solubility. The DPA units are connected to position 4 of the fluorophore via a triazine-ethylenediamine spacer. Fluorescence titration studies of the chemosensor revealed a high selectivity for Cu2+ over other divalent ions, the emissions were strongly quenched upon binding, and a stability constant of 5.52 log units was obtained. Given the distance from DPA chelating units and the fluorophore, quenching from the Cu2+ complexation suggests an electron transfer or an electronic energy transfer mechanism. Furthermore, the Cu2+-sensor complex proved to be capable of sensing anionic phosphate derivatives through the displacement of the Cu2+ cation, which translated into a full recovery of the luminescence from the naphthalimide. Super-resolution fluorescence microscopy studies performed in HeLa cells showed there was a high intracellular uptake of the chemosensor. Incubation in Cu2+ spiked media revealed a strong fluorescent signal from mitochondria and cell membranes, which is consistent with a high concentration of ATP at these intracellular sites.
Highlights
The field of chemosensors has experienced a “boom”, mainly due to the appearance of coordination compounds bearing fluorophores, which correlate their luminescence to the amount of cation bound to the chelating/receptor unit.Over the past few decades, a multitude of chemosensor systems that are capable of detecting metal cations and anions have been developed for biological applications
A currently employed strategy is the use of chelating moieties coupled with fluorophores that are capable of coordinating metal cations, which are subsequently used to bind anionic species in a sequential manner, mainly by taking advantage of the strength of the coordination bond (Figure 1a)
For the synthesis of the fluorophore, we took advantage of the chemical versatility of the central 1,8-naphthlic core, which allows for facile introduction of any terminal amine
Summary
Over the past few decades, a multitude of chemosensor systems that are capable of detecting metal cations and anions have been developed for biological applications. A currently employed strategy is the use of chelating moieties coupled with fluorophores that are capable of coordinating metal cations, which are subsequently used to bind anionic species in a sequential manner, mainly by taking advantage of the strength of the coordination bond (Figure 1a). The scientific community has focused on detecting phosphate derivatives because of their relevant role in biologic systems, especially in the regulation of metabolic mechanisms in cells [5]. There are many examples of this, including the use of cyclam [6,7], cyclen [8,9,10] and other
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
