Author(s): Moro, Artur J. ; Santos, Miguel ; Outis, Mani ; Mateus, Pedro ; Pereira, Pedro Matos
Date: 2020
Persistent ID: http://hdl.handle.net/10362/116889
Origin: Repositório Institucional da UNL
Subject(s): copper (II); fluorescent chemosensor; naphthalimide; phosphate derivatives; super-resolution fluorescence microscopy; Clinical Biochemistry
UIDB/50006/2020 SFRH/BD/120985/2016 Project LISBOA-01-0145-FEDER-007660 PPBI-POCI-01-0145-FEDER-022122 DL 57-021/DL/2018 ROTEIRO/0031/2013-PINFRA/22161/2016
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.
