Ratiometric Detection Of Cu2 Research Articles

A Logic Fluorescent Chemosensor Based on Eu3+ Functionalized Cd‐MOFs for Sensing Fe3+ and Cu2+ Synchronously

AbstractOne of the most critical and yet unsolved issues is the effective monitoring of multiple heavy metal ions in complex systems through their specific function in fluorescence detection. In this work, luminescence‐active cadmium base metal‐organic frameworks (Cd‐MOFs) based on the planar and rigid π‐conjugated structure ligand benzo‐(1,2;3,4;5,6)‐tris (thiophene‐2’‐carboxylic acid) (H3BTTC) was chosen. A series of sensing experiments demonstrated that the Cd‐MOFs exhibits selective and sensitive response for Fe3+ and Eu3+ through fluorescence “turn off” and “antenna effect” respectively. In addition, the encapsulation of Eu3+ inside the Cd‐MOFs (Eu3+@Cd‐MOFs) led to an excellent probe with dual emission. To this end, a programmable fluorescence platform was developed to detect Fe3+ and Cu2+, in which the emission peaks of both the ligand and Eu3+ are completely quenched by Fe3+. The ratiometric detection of Cu2+ leads to a decrease in Eu3+ emission, while the ligand emission remains stable. To demonstrate the strategy, the fluorescence (Output) of Cd‐MOFs, Eu3+@Cd‐MOFs, and the analytes (Eu3+, Fe3+, and Cu2+, input) achieved elementary Boolean logic operations (OR, NOR, AND) and they constitute a logic fluorescent chemosensor to analyze Fe3+ and Cu2+ synchronously.

A specific short peptide-assisted enhanced chemiluminescence resonance energy transfer (CRET) for label-free and ratiometric detection of copper ions in complex samples

Convenient and rapid detection of Cu2+ in serum has important clinical significance for related diseases. Herein, a ratiometric detection of Cu2+ based on specific short peptide (SPGH)-assisted enhanced chemiluminescence resonance energy transfer (CRET) has been constructed. An interesting phenomenon that tetra-peptide with the sequence of Ser-Pro-Gly-His (SPGH) was able to specifically and remarkably enhance the catalytic performance of Cu2+ has been discovered, the enhancement mechanism is mainly due to the significant increasing generation of Cu2+-induced hydroxyl radical after addition of SPGH. The chemiluminescence (CL) of the luminol-H2O2 system was efficiently catalyzed by the formed Cu(SPGH)2 complex, which acts as an internal light source to triggers on the fluorescence of QDs via CRET, allowing the ratiometric detection of Cu2+ within 15 min with improved selectivity and sensitivity. The relative standard deviation was lower than 6.38 % due to the ratiometric signal improving its anti-interference ability. Importantly, it is feasible to detect total Cu in human serum, and the results were consistent with that of ICP-AES (r = 0.9321, n=55). The reliable, rapid, yet simple ratiometric detection of Cu2+ in serum based on SPGH-assisted enhanced CRET provides a promising potential alternative method for Cu2+ detection in clinical application.

A dual-functional probe for sensing pH change and ratiometric detection of Cu2.

A series of benzothiazole-based compounds were synthesized and characterized. Among them, probe Z showed significant dual-functional performance which was capable of sensing pH change and Cu2+. Probe Z displayed fluorescent turn-on under alkaline conditions due to deprotonation of the hydroxyl group along with the obviously color change from colorless to mint green. Interestingly, it further achieved in ratiometric detection of Cu2+ through absorbance or fluorescence signals in strong alkaline condition. The limit of detection was calculated correspondingly as 0.37μM and 1.35μM, respectively. Especially, the combination of the XNOR and INHIBIT logic gates could be used to confirm that one medium was in neutrality or alkalinity condition. Moreover, Z was successfully used in real water samples and test paper for fast identification of Cu2+, respectively.

A dual-functional chemosensor for fluorescent on-off and ratiometric detection of Cu2+ and Hg2+ and its application in cell imaging

A dual-functional chemosensor BHMB was synthesized and characterized. It showed highly selectivity through significant fluorescence turn-off and obvious color change towards Cu2+ and Hg2+, respectively. The binding ratios of BHMB to Cu2+ and Hg2+ confirmed by job’ plot were 2:1 and 1:1, respectively. Moreover, the detection of limit of BHMB to Cu2+ and Hg2+ was confirmed as 4.47 × 10−8 M and 6.72 × 10−7 M, respectively. Especially, BHMB was successfully used in test paper for fast identification of Cu2+ and Hg2+, logic gate construction and cell imaging in human stromal cell (HSC).

Ultrasensitive Colorimetric and Ratiometric Detection of Cu2+: Acid-Base Properties, Complexation, and Binding Studies.

Herein, we report the synthesis and characterization of a chemosensor, 5-(diethylamino)-2-(2,3-dihydro-1H-perimidin-2-yl)phenol (HL), synthesized from a condensation between 4-(diethylamino)salicylaldehyde and 1,8-diaminonaphthalene. Upon investigation of the sensing properties of HL, it was found that this sensor may be employed for simple yet efficient detection of Cu2+ in aqueous methanol solutions. The selective and ratiometric response to Cu2+ yielded an outstandingly low limit of detection of 3.7 nM by spectrophotometry and is also useful as a naked-eye sensor from 2.5 μM. The system was studied by spectrophotometric pH titrations to determine Cu2+ binding constants and complex speciation. Binding of Cu2+ to HL occurs in 1:1 stoichiometry, in good agreement with high-resolution electrospray ionization mass spectrometry (ESI-HRMS) results, Cu2+ titrations, and Job’s plot experiments, while the coordination geometry was tentatively assigned as square pyramidal by spectroscopic studies.

1,8-Naphthalimide derived dual-functioning fluorescent probe for “turn-off” and ratiometric detection of Cu2+ based on two distinct mechanisms in different concentration ranges

In this study, a novel 1,8-naphthalimide derived compound bearing the coumarin moiety called 7-Diethylaminocoumarin-3-aceone (N-hydroxyethyl-1’,8’-naphthalimide-4’-) hydrazone (1) has been designed, synthesized and evaluated as a dual-functioning fluorescent probe for “turn-off” and ratiometric detection of Cu2+ based on two distinct mechanisms in different concentration ranges in aqueous solution. This probe 1 showed high selectivity and sensitivity for Cu2+ over other common metal ions, for the limit of detection (LOD) could reach 3.90 × 10−8 M and 3.26 × 10−7 M for “turn-off” and ratiometric detection respectively. Moreover, in Cu2+ equivalence range of 0–0.5, a decrease in fluorescence emission intensity at 441 nm was observed upon addition of Cu2+, but in Cu2+ equivalence range of over 0.5, a new emission band centered at 462 nm appeared with increasing intensity accompanied by a decrease in fluorescence emission intensity at 570 nm, which provided ratiometric fluorescence detection of Cu2+. The sensing mechanisms for the responses of 1 to Cu2+ were chelation-quenched fluorescence (CHQF) and chemical reaction between 1 and Cu2+ over Cu2+ equivalence range of 0–0.5 and more than 0.5, respectively. Thus, this probe 1 could be utilized for sensing and monitoring Cu2+ in environmental and biological systems in different concentration ranges.

Highly selective and sensitive determination of copper ion based on a visual fluorescence method

A novel ratiometric fluorescence sensor for rapid and on-site visual detection of Cu2+ was designed and synthesized by integrating yellow-emission rhodamine fluorophore (RL) and red-emission CdTe@SiO2 QDs. The as-prepared nanohybrid fluorescence sensor shows dual-emissions at 537nm and 654nm under a single excitation at 500nm in the presence of Cu2+. Owing to the strong chelating ability of RL toward Cu2+, the yellow fluorescence of RL could be selectively enhanced while the red fluorescence of CdTe QDs is almost unchanged, leading to an obvious fluorescence color change from red to yellow, which could be used for visual and ratiometric detection of Cu2+. This nanohybrid sensor exhibits excellent selectivity, sensitivity and anti-interference to Cu2+ detection and the detection limit is as low as 8.4nM. Additionally, a simple device test strip for rapid and on-site detection of Cu2+ has been designed by immobilizing the RL-CdTe@SiO2 QDs on a common filter paper. This simple and effective paper-based sensor has a visual detection limit of 0.5μM, showing its promising application for on-site and rapid sensing of Cu2+ in pollution water.

A CHEF-based biocompatible turn ON ratiometric sensor for sensitive and selective probing of Cu2+

The newly synthesized 1-amino-2-naphthol functionalized fluorophoric ligand L1 specifically binds Cu2+ in presence of large excess of other competing ions with observable changes in their electronic and fluorescence spectral behavior. These spectral changes are significant enough in visible region of the spectrum and thus enable naked eye detection. As L1 displays Cu2+ ions dependent spectral changes at two different wavelengths of the emission spectra so it can be used as a ratiometric sensor for the analyte with minimal interference of environmental conditions and background disturbances. The coordination of Cu2+ with L1 force the molecule to attain a planar geometry with an increased opportunity of charge transfer throughout the π-system, leading to a highly conjugated geometry with sufficient enhancement of the fluorescence intensity, from which fluorogenic and ratiometric detection of Cu2+ ions are possible. Further, fluorescence microscopic studies confirmed that the reagent L1 could also be used as an imaging probe for detection and uptake of Cu2+ ions in HeLa cells.