Colorimetric Fluorescent Probe Research Articles

Embedding dual fluoroprobe in metal-organic frameworks for continuous visual recognition of Pb2+ and PO43- via fluorescence 'turn-off-on' response: Agar test paper and fingerprint

A novel dual-emissive ratiometric fluorescence (RF) probe CDs/QDs@ZIF-8 has been successfully constructed by employing a simple and effective strategy for in situ encapsulating carbon dots (CDs) and thioglycolic acid-modified CdTe quantum dots (QDs) into porous metal-organic frameworks (MOFs) "cage". The dual responsive colorimetric fluorescence probe was developed for the ultra-high selectivity and sensitivity continuous detection of Pb2+ (turn OFF) and PO43− (turn ON) in biological samples. Blue CDs acts as a stable internal standard emission, the emission color of CDs/QDs@ZIF-8 changes from red to blue with introducing Pb2+, fluorescence of probe is quenched because of the binding of Pb2+ ions to thioglycolic acid on the surface of probe and e- transfer from the photoexcited QDs to Pb2+ ions, color can be recovered after the adding PO43− to CDs/QDs@ZIF-8-Pb2+ system, which could take away Pb2+ ions from the surface of CDs/QDs@ZIF-8. More importantly, fabricated agar test papers was also successfully applied in visual detection of Pb2+ and PO43- in real samples, which can implement without instrument-specific calibration.

Ratiometric and colorimetric fluorescent probe for hypochlorite monitor and application for bioimaging in living cells, bacteria and zebrafish

Hypochlorous acid (HOCl)/hypochlorite (ClO−) was a biologically important component of reactive oxygen species (ROS) and plays a key role in human immune function systems. HOCl/ClO− can destroy invasive bacteria and pathogens, and mediate the physiological balance of the organism with low concentrations, and cause oxidation of the biomolecules such as proteins, cholesterol and nucleic acid in biological cells, leading to a series of diseases with over capacity. Therefore, quantifying the content of HOCl/ClO− in organisms are extremely urgent. In this work, coumarin-salicylic hydrazide Schiff base (CMSH), a ratiometric and colorimetric fluorescent probe for ClO- detection based on coumarin as the fluorophore unit was rationally designed and synthesized. The results indicated that CMSH exhibits high selectivity and sensitivity for ClO- identification. Additionally, the ratios (I470/I532) displayed brilliant ClO−-dependent quick and sensitive performance within 40 s and limitation of 128 nM, respectively. As well as the color of the solution changes from green to colorless accompanied by the fluorescence form green turns into blue with addition of ClO−. Totally, CMSH has been successfully employed as ratiometric sensor to image in living cells, bacteria and zebrafish with low cytotoxicity and good permeability.

Two novel colorimetric fluorescent probes: Hg2+ and Al3+ in the visual colorimetric recognition environment.

Two new dual channel Schiff base fluorescent probes, Tri-R6G and Tri-Flu, were synthesized, and can detect Hg2+ and Al3+, respectively. The two probes were characterized by FTIR, 1H NMR, 13C NMR and HRMS, and their optical properties were detected by UV and FL. Test results showed the probes' detection of Hg2+ and Al3+ compared to other metal ions (Ag+, Co2+, Cd2+, Mg2+, Cu2+, Ni2+, Ba2+, Pb2+, Cr3+, Al3+, Zn2+, Hg2+, K+, Ga2+ and Fe3+), respectively. Besides, the detection limits were determined to be 1.61 × 10−8 M and 1.15 × 10−8 M through the standard curve plot, respectively. The photoelectron transfer (PET) mechanism was guessed by the Job's plot and the infrared titration. Corresponding orbital electron distribution and molecular geometry configurations of the compounds were predicted by density functional theory (DFT). In addition, the prepared test paper changed from white to pink when the target ion was detected. The color changed from colorless to pink in a solution having a concentration of 10−5 M.

A highly selective colorimetric fluorescence probe for Cu2+ in aqueous media: the synthesis, DFT investigation and its application in living cells

A novel highly selective colorimetric fluorescence probe, POPH, has been successfully synthesized and it shows remarkable selective and sensitive response to Cu2+ in aqueous media (HEPES buffer, pH = 7.4).

Understanding fluorometric interactions in ion-responsive sustainable polymer nanocomposite scaffolds.

The fluorescent colour in biodegradable and biocompatible flexible polymer nanocomposite gels was modulated in order to gain insight into the interfacial interactions of functional scaffolds with metal ions. The hybrid nanomaterials were introduced into the polymer matrix to obtain mechanically robust porous morphologies where the intrinsic luminescence matrix was found to critically enhance the threshold of the visual detection limits. The quenching of fluorescence intensity has been predominantly attributed to the interactions of functional receptors of luminescent nanofillers with respect to the chromophores of the fluorescent matrix. The chromium ion is selected to understand the change in fluorescence intensity of the nanocomposite gel with the degree of metal ion adsorption. The number of functional nanomaterials loaded into the matrix and the luminescence nature of the base polymer are varied with the purpose of gaining insight into the remote sensing mechanism of the colorimetric fluorescent probe.

An ICT-based fluorescent probe for the detection of fluoride ions in cellular mitochondria

A novel colorimetric fluorescent probe Mito-PF was constructed base on ICT strategy, which showed a 30-fold enhancement of fluorescence intensity toward fluoride ion (F−) with excellent sensitivity and high selectivity. The response of the probe to fluoride ion is ascribed to the cleavage reaction of SiO bond, then releases fluorescent group with intense green fluorescence signals realizing turn-on fluorescence responses. Probe Mito-PF shows good cell membrane permeability and can be successfully located in mitochondria to monitor fluoride ion in living cells, which is of great significance for biological research and clinical diagnostic.

A colorimetric fluorescent probe for rapid and specific detection of nitrite.

The method of fluorescent probes has been an important technique for detection of nitrite (NO2 - ). As an important inorganic salt, excessive nitrite would threaten humans and the environment. In this paper, a colorimetric fluorescent probe P-N (1,2-diaminoanthraquinone) with rapid response and high selectivity, which could detect NO2 - by visual colour changes and fluorescence spectroscopy is presented. The probe P-N solution (pH 1) changed from pink to colourless with the addition of NO2 - and fluorescence intensity at 639nm clearly decreased. Good linear exists between fluorescence intensities and NO2 - concentrations for the range 0-16μM, and the detection limit was 54nM (based on a 3σ/slope). Moreover, probe P-N could also detect NO2 - in real water samples, and results were all satisfactory. Probe P-N shows great practical application value for detecting NO2 - in the environment.

A Novel Colorimetric Fluorescent Probe for Fe3+ Based on Tetraphenylethylene-rhodamine

Abstract A novel tetraphenylethylene-rhodamine-based fluorescent probe amide compound L was synthesized and its sensing properties of metal ions were investigated. It exhibited high sensitivity and high selectivity toward Fe3+ compared with other common metal ions in EtOH-H2O (50 μM, 3:2, V/V, pH 7.0). A fluorescence quenching ratio of 92% at 482 nm and 254-fold enhancement of fluorescence intensity at 582 nm were achieved upon the addition of 4.0 equiv. Fe3+. Under optimal experimental conditions, the fluorescence intensity of probe exhibited a dynamic response range for Fe3+ from 2.0 × 10−5 M to 1.5 × 10−4 M at 482 nm and 3.0 × 10−5 M to 1.5 × 10−4 M at 582 nm, respectively, with a detection limit of 1.56 × 10−7 M. Meanwhile, the binding ratio of L and Fe3+ was confirmed to be 1:1 by electrospray ionization-mass spectrometry (ESI-MS) analysis of L-Fe3+ complex and Benesi-Hildebrand method. According to 1H-nuclear magnetic resonance (NMR) titration and scanning electron microscopy results, the coordination mechanism of probe L with Fe3+ was further elucidated. The binding of Fe3+ to L not only led to the aggregation state dispersed and fluorescence quenching at 482 nm, but also induced spirolactum ring opening of rhodamine and aroused a 254 times fluorescence enhancement at 582 nm together with color variation from colorless to red purple. The developed sensor was successfully employed to determine Fe3+ ion in water samples and proved to be selective and sensitive.

A long-wavelength ultrasensitive colorimetric fluorescent probe for carbon monoxide detection in living cells.

Exploring techniques for monitoring the intracellular signaling molecule carbon monoxide (CO) in biosystems is important to help understand its various cellular functions. Therefore, a simple long-wavelength colorimetric fluorescent probe LW-CO was designed for selectively and sensitively detecting intracellular CO in living systems. Probe LW-CO is ultrasensitive and can track CO levels in the range of 0-1 μM, with a detection limit of about 3.2 nM. Additionally, the obvious color changes of probe LW-CO with CO (yellow to pink) provide a convenient way for on-site detection of CO with the naked eye. Probe LW-CO was applied to track the exogenous levels of CO in RAW264.7 cells. Probe LW-CO proved to be an efficient method for investigating various cellular functions of CO.

A novel ratiometric and colorimetric fluorescent probe for hypochlorite based on cyanobiphenyl and its applications.

Reported here is a novel ratiometric and colorimetric fluorescent probe 1 for hypochlorite based on cyanobiphenyl and diaminomaleonitrile. This probe 1 was designed based on the mechanism that ClO- selectively cleaved the hydrazone bond (-C=N-) in this probe and released the fluorophore, 3`-formyl-4`-hydroxy-4-biphenylcarbonitrile. The addition of ClO- to the solution of probe 1 resulted in a very large blue-shift in both fluorescence (107 nm) spectra and an obvious fluorescence color change from red to green. Furthermore, this probe displays a rapid response (30 s) and a low detection limit (3.34 × 10-7 M, based on LOD = 3σ/slope) in detecting ClO-. Importantly, practical utility of this probe for the selective detection of ClO- in living cells has been successfully demonstrated, illustrating the great potential for biological analysis. Additionally, the probe 1 was also successfully applied to the detection of ClO- in real water sample.

Dual-functional colorimetric fluorescent probe for sequential Cu2+ and S2− detection in bio-imaging

It is highly indispensable to detect Cu2+ and S2− because of its vital role in living organisms and the environment. In this work, a novel “on-off-on” coumarin-based colorimetric fluorescent probe L for sequential recognition of Cu2+ and S2– was strategically designed and synthesized. It displays low detection limit measured to be 2 × 10−8 M and 6 × 10−8 M respectively for Cu2+ and S2– with high selectivity and excellent sensitivity. In addition, an appropriate broad pH of 4–10 allows probe L to be applied to the biological window, and MTT experiments show that probe L has negligible cytotoxicity, which demonstrate it can be employed to determine Cu2+ and S2– in A375 cells.

A rapid and visible colorimetric fluorescent probe for benzenethiol flavor detection

Benzenethiols are a class of flavoring ingredients used in the food, pharmaceutical, cosmetics and chemical industries. A rapid and visible colorimetric fluorescent probe was developed for the detection of benzenethiol flavors. It provides rapid quantitative detection of benzenethiols at low levels, down to a limit of 10 nM. Test paper containing the probe changes color according to benzenethiol concentration (from colorless to pink, visible with the naked eye). The probe was also successfully used to test benzenethiol concentrations in real food samples. This study demonstrates that this novel probe can be employed as a benzenethiol testing tool.

Colorimetric fluorescence probe detecting Hg2+ and OCl– based on intramolecular charge transfer and excited-state intramolecular proton transfer mechanisms

The recognition and detection of Hg2+ and OCl– have been subjected to extensively attention, since these ions can cause extremely adverse effects on living body. Recently, a novel fluorescence probe molecule simultaneously detecting Hg2+ and OCl– ions had been researched in experiment, while a carefully molecular-level theoretical investigation was lacking. In this work, the photochemical and photophysical processes in excited state were researched for title species, the corresponding sensing mechanism was reported detailedly for the first time. The computational data of absorption and emission spectra agreed well with experimental results. The calculated hydrogen bond parameters and the visualized reduced density gradient isosurfaces indicated that the strengthening hydrogen bond in excited state facilitated the occurrence of the excited-state intramolecular proton transfer (ESIPT) reactions. The fluorescence signal that detected Hg2+ ion was also reassigned in our research, which originated from photoisomeric structure S-P instead of enol form S-N. The ESIPT mechanism was quantitatively explained by calculating the reactive Gibbs free energies. Finally, the frontier molecular orbitals and overlap between hole and electron analyses confirmed that the interaction between probe molecule and analytes impeded the excited-state intramolecular charge transfer (ESICT) behavior. Essential comprehending for ESICT and ESIPT properties were helpful in illuminating the probing mechanism, and to design an excellent fluorescence probe molecule.

A novel ratiometric and colorimetric fluorescent probe for hydrazine based on ring-opening reaction and its applications

In recent years, with the increasing awareness of environmental protection, the detection of industrial emissions has become more and more strict. Hydrazine, as a common reactive group, the excessive emissions by the widespread use is inevitably harmful to the environment and human beings. To respond positively to environment protection policies at home and abroad, the development of a convenient and effective hydrazine probe has become an important subject for many research groups. In this work, a derivative containing lactone ring was synthesized based on naphthalimide. This probe displayed a fast colorimetric and ratiometric fluorescent response for hydrazine with high selectivity and sensitivity based on the ring-opening reaction. The detection limit of the probe for hydrazine is about 0.2032 μM (<10 ppb). It is worth mentioning that the probe can successfully apply to detect gaseous hydrazine when the probe is loaded on the periopaper. Furthermore, the results of biological imaging experiment indicated that the probe can detect the hydrazine at the cellular level.

A large Stokes shift, sequential, colorimetric fluorescent probe for sensing Cu2+/S2- and its applications

Copper ions (Cu2+) and sulfide (S2−) are important markers in many physiologies and pathological processes. In this work, a new near-infrared fluorescent probe 1 for colorimetric and sequential detection of Cu2+/S2− was designed and developed. The probe showed a rapid (less than 1 min), highly selective and sensitive response toward copper ions. Notably, the probe could also be applied to detect S2− through reversible formation-separation of complex 1-Cu2+ and CuS with a large Stokes shift of 234 nm. The detection limit for Cu2+ and S2− was found to be 1.8 × 10-8 M and 1.5 × 10-8 M, respectively. Furthermore, the binding stoichiometry between 1 and Cu2+ was found to be 1:1, the binding mode was also demonstrated using density functional theory (DFT) calculations and contrastive compound research. In addition, the probe was successfully applied in real water samples assay for the detection of Cu2+, and the strip papers experiments also showed that probe 1 can be used to detect Cu2+ and S2−.

A Visible Colorimetric Fluorescent Probe for Hydrogen Sulfide Detection in Wine.

A new efficient and practical fluorescent probe 6-(benzo[d]thiazol-2-yl)naphthalen-2-yl-thiophene-2-carboxylate (probe 1) was synthesized to detect hydrogen sulfide (H2S). The addition of H2S caused the solution of probe 1 to change from colorless to yellow, and the solution of probe 1 changes to different colors with respect to different concentrations of H2S. Importantly, probe 1 could help detect H2S efficiently by a distinct color response as a visible detection agent. Probe 1 reacted with various concentrations of H2S (0–200 μM), and the detection limit for H2S was 0.10 μM. Particularly, probe 1 can be applied as a sensor to detect H2S accurately in wine samples.

A novel water-soluble naked-eye probe with a large Stokes shift for selective optical sensing of Hg2+ and its application in water samples and living cells.

A water-soluble and colorimetric fluorescent probe with a large Stokes shift (139 nm) for rapidly detecting Hg2+, namely Hcy-mP, was synthesized by using an indole derivative and 2,4-dihydroxybenzaldehyde as starting materials. This probe demonstrates good selectivity for Hg2+ over other metal ions including Ag+, Pb2+, Cd2+, Cr3+, Zn2+, Fe3+, Co2+, Ni2+, Cu2+, K+, Na+, Mg2+, and Ca2+ in aqueous solution. With the increase in concentration of Hg2+, the color of the solution changed from pale yellow to pink and the fluorescence intensity decreased slightly. When 5-equivalents of EDTA were added to the solution with Hg2+, the fluorescence intensity of this probe was restored. The probe has been applied to the detection of Hg2+ in real water samples. Moreover, this probe was confirmed to have low cytotoxicity and excellent cell membrane permeability. The effect of Hcy-mP–Hg2+ towards living cells by confocal fluorescence was also investigated.

在双波长下识别Fe3+的一种新型可视化荧光探针的合成及性能

在双波长下识别Fe³⁺的一种新型可视化荧光探针的合成及性能

A highly selective colorimetric fluorescent probe for detection of Hg2+ and its application on test strips.

An efficient fluorescent probe Pyr-Rhy based on pyrazole was developed, which can detect Hg2+ in water. Its fluorescence properties were studied by UV-vis and fluorescence spectroscopy, and the study results indicated that this probe can selectively detect Hg2+via complexation reaction, and then cause a remarkable color change from colorless to pink and a strong fluorescence enhancement can be observed. Furthermore, this probe showed high sensitivity with the detection limit down to 2.07 × 10−8 M, and its stoichiometric ratio toward Hg2+ ions was 1 : 1. The sensing mechanism was investigated by Job's plot 1H NMR titrations, and FT-IR spectra analysis, which demonstrated a chelation-enhanced fluorescence (CHEF) mechanism. More importantly, obvious color changes of sensor Pyr-Rhy can be observed when it was impregnated on filter paper testing strips and immersed in Hg2+ solution (water as solution), indicating its potential application for trace Hg2+ detection in environmental samples.

Design and synthesis of a novel colorimetric fluorescent probe for the selective detection of sulfur dioxide in SH-SY5Y neuroblastoma cells and its applications in traditional Chinese medicines

A fast response time, low limit of detection and high fluorescence quantum yield probe DTCC was designed and synthesized to detect SO2 derivatives based on coumarin-thiophene dye which was fused with a coumarin moiety and 2-thiophenecarboxaldehyde.