Search

Copper is an essential element in living organisms and the monitoring of copper ions in aquatic environments and biological systems is of great significance. Inspired by a family of visible light responsive photoswitchable compounds, we report here a fluorescent probe (HTI-Q) for Cu2+ with excellent selectivity, high sensitivity, and a limit of detection (LOD) of ca. 0.02 μM. While the central carbon-carbon double bond of HTI-Q is photoisomerizable between the Z and E configurations, it is locked upon binding with Cu2+ into the E configuration, resulting in a large bathochromic shift (102 nm) and ratiometric fluorescence changes. Different sensing modes were demonstrated including in mixed solvents, a two-phase sensing system containing cation exchanger, and fluorescent nanoprobes containing a reference dye. The absorbance change of HTI-Q upon 470 nm light illumination also depended on the concentration of Cu2+. HTI-Q-based sensors were successfully applied to determine Cu2+ in real water samples with excellent recovery. Further, fluorescent nanoprobes incorporating HTI-Q were successfully applied to image endolysosomal Cu2+ changes upon external stimulation. [Display omitted] • A photoswitchable Cu2+ probe (HTI-Q) was proposed for the first time based on hemithioindigo. • HTI-Q offered tunable sensitivity, high selectivity, and several different optical sensing modes. • Nanoprobes containing HTI-Q were successfully applied for subcellular fluorescence imaging in the endolysosomes. [ABSTRACT FROM AUTHOR]

Based on fluorescent resonance energy transfer (FRET), we developed a ratiometric fluorescent probe 1 for sensing Cu 2+ . As expected, probe 1 exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Cu 2+ in aqueous solution. A significant color change from pale yellow to pink could be observed, enabling naked-eye detection of Cu 2+ . Furthermore, fluorescence imaging experiment of Cu 2+ in living MGC-803 cells demonstrated its value of practical applications in biological systems. [ABSTRACT FROM AUTHOR]

Copper is a trace metal nutrient essential for most forms of life. The dysregulation of copper homeostasis is associated with various diseases, such as Menkes disease, Alzheimer's disease, Wilson disease, gastrointestinal disorders, and kidney damage. Therefore, detection of copper ions in biological system is of great significance for fundamental study in biology and medicine field. To address this critical need, we herein developed a novel flavonoid-based bioprobe 6-(bis(pyridin-2-ylmethyl)amino)-2-(4-(dimethylamino)phenyl)-3-methoxy-4H-chromen-4-one ( DPA-FL ) for copper detection. The DPA-FL showed highly fluorescent response towards copper ions with a high tolerance of other competitive metal ions. The fluorescence intensity at 510 nm are linearly proportional to the amount of Cu 2+ from 0 to 10 μM with a detection limit lower than 100 nM (S/N rule). The intracellular recognition of copper ions was successfully achieved in HUVECs. Furthermore, the DPA-FL-Cu 2+ complex could also be used for secondary sensing of pyrophosphate in living cells, thus providing a powerful imaging tool for tracking of copper ions and pyrophosphate in biological system. [ABSTRACT FROM AUTHOR]

A new fluorescent sensor 6-(2,3-dihydroxyphenyl)-5,6-dihydrobenzoimidazo[1,2-c] quinazoline (H 2 L) and the Zn(II) complex [Zn 2 L 1 2 ]∙C 2 H 5 OH (H 2 L 1 = 3-{[2-(1 H -benzoimidazol-2-yl)-phenylimino]-methyl}-benzene-1,2-diol) ( 1 ) were synthesized and characterized by single-crystal X-ray diffraction. H 2 L can be used to recognize Cu 2+ in aqueous media as an on–off fluorescent sensor, forming the Cu(II) Schiff-base complex (CuL 1 ). Furthermore, CuL 1 can serve as an off–on fluorescent sensor to detect histidine (His) via the ligand displacement approach. The sequential detection of Cu(II) and histidine shows on–off–on phenomenon. The crystal structure of the dinuclear Zn(II) complex indicates that the coordination of H 2 L with Zn(II) promotes C N bond breakage, resulting in the quinazoline ring-opening of H 2 L to form the Zn(II) Schiff-base complex ( 1 ). The experimental results proved that H + can also assist the ring-opening of H 2 L to form a Schiff base, H 2 L 1 . H 2 L is stable in neutral and weak basic solutions. This is further confirmed by the theoretical calculations. The cell imaging studies indicated that H 2 L and CuL 1 can be used to detect the intracellular Cu 2+ ion and His under physiological conditions, respectively. CuL 1 can also be used to determine His in urine. [ABSTRACT FROM AUTHOR]