A novel carbazole-based mitochondria-targeted ratiometric fluorescent probe for bisulfite in living cells

A near-infrared AIE fluorescent probe for accurate detection of sulfur dioxide derivatives and visualization of fingerprints

In most biophysiological processes, sulfur dioxide (SO2) is an important intracellular signaling molecule that plays an important role. The change of SO2 in cells are closely related to various diseases such as neurological disorders and lung cancer, so it is necessary to develop fluorescent probes with the ability to accurately detect SO2 during physiological processes. In this work, we designed and synthesized a multifunctional fluorescent probe TIS. TIS has excellent properties such as near-infrared emission, large stokes shift, excellent SO2 detection capabilities, low detection limit, high specificity and visualization of color change before and after reaction. Simultaneously, TIS has low cytotoxicity, good biocompatibility, clear cell imaging capability and mitochondrial targeting ability. In addition, the ability of TIS to be applied to different material surfaces for latent fingerprint fluorescence imaging was also explored. TIS provides an excellent method for the accurate detection of SO2 derivatives and shows great potential applications in near-infrared cellular imaging and latent fingerprint fluorescence imaging.

Recent synthetic strategies for the construction of functionalized carbazoles and their heterocyclic motifs enabled by Lewis acids

This article demonstrates recent innovative cascade annulation methods for preparing functionalized carbazoles and their related polyaromatic heterocyclic compounds enabled by Lewis acid catalysts. Highly substituted carbazole scaffolds were synthesized via Lewis acid mediated Friedel-Crafts arylation, electrocyclization, intramolecular cyclization, cycloaddition, C-N bond-formations, aromatization and cascade domino reactions, metal-catalyzed, iodine catalyzed reactions and multi-component reactions. This review article mainly focuses on Lewis acid-mediated recent synthetic methods to access a variety of electron-rich and electron-poor functional groups substituted carbazole frameworks in one-pot reactions. Polyaromatic carbazole and their related nitrogen-based heterocyclic compounds were found in several synthetic applications in pharma industries, energy devices, and materials sciences. Moreover, the review paper briefly summarised new synthetic strategies of carbazole preparation approaches will assist academic and pharma industries in identifying innovative protocols for producing poly-functionalized carbazoles and related highly complex heterocyclic compounds and discovering active pharmaceutical drugs or carbazole-based alkaloids and natural products.

The Detection and Imaging of pH Values in Living Cells with Hemicyanine Based Colorimetric Mitochondria-Targeted Fluorescent Probe

pH plays a crucial role in cells, especially mitochondria, an important organelle. Developing probes with well-performance for pH detection is still in great demand. Therefore, we first synthesized an indole-based probe (MC-ID-OL) to detect mitochondrial pH changes. The emission wavelength of MC-ID-OL is 649 nm, which does not reach the near-infrared region (650-900 nm). To further enlarge the emission wavelength, probe MC-BI-OL was developed by replacing indolenine with benzoindole. As expected, the emission wavelength changed from 649 to 656 nm. MC-BI-OL probes could also detect pH changes and mitochondria's highly reversible proportional fluorescence localization. In addition, the fluorescence imaging of the MC-BI-OL in HeLa cells demonstrated that this probe could sense changes in the pH of mitochondria in cells.

A ratiometric water-soluble fluorescent probe for the detection of sulfur dioxide derivative in sinusitis mice model

Sulfur dioxide (SO₂) plays an extremely important role in the basic processes of physiology and pathology. As an antioxidant, SO₂ can maintain the redox homeostasis in the cell. Excessive inhalation of SO₂ would lead to irreparable respiratory damage, resulting in respiratory diseases, neurological disorders, and even cardiovascular disease. Thus, it is urgent to exploit an excellent way to monitor SO₂ derivatives in biological system. Herein, we design a water-soluble ratiometric fluorescent probe to fast detect the level of SO₂ derivatives in living cells in vivo. The probe displays obvious fluorescence signal at long wavelength, which is helpful for imaging of biological system. After respond to SO₂ derivatives, the fluorescence signal at 465 nm increases rapidly due to the Michael addition reaction is triggered, further causing the disruption of large conjugated system. The probe exhibits high selectivity and fast respond to SO₂ derivatives, which can be able to sensitive and real-time monitoring of SO₂ derivatives level in living cells. Moreover, the probe reveals a low detection limit and a great linear relationship to SO₂ derivatives. Based on the negligible cytotoxicity and good biocompatibility of the probe, which is employed to detect exogenous and endogenous SO₂ derivatives in living cells. In addition, it is also served as a potential chemical tool to detect SO₂ derivatives in mice model of sinusitis.

Novel styrylbenzimidazolium-based fluorescent probe for reactive sulfur species: Selectively distinguishing between bisulfite and thiol amino acids

In this study, a new fluorescent probe containing dicyanovinyl moiety has been designed and synthesized. Fluorescent probe based on styrylbenzimidazolium derivative was reported for the effective detection of bisulfite and distinguish it from biothiols by exploiting dicyanovinyl group as the recognition site. The photophysical properties of the novel styrylbenzimidazolium derivative were assessed by determination of absorption and fluorescence spectra, fluorescence quantum yield, and fluorescence lifetime. Its spectroscopic behavior towards various analytes has been evaluated in aqueous media at a pH of 7.4. The highest increase in fluorescence intensity of compound 5 in the presence of different analytes was observed for sodium bisulfite and the limit of detection was estimated to be 0.25 μM. The styrylbenzimidazolium dye was applied to detect bisulfite in various wine sample using fluorimetry. Finally, the ability of this novel probe to detect HSO₃^- in red wine samples was evaluated.

Intramolecular Oxidative Diaryl Coupling of Tetrasubstituted Diphenylamines for the Preparation of Bis(trifluoromethyl) Dimethyl Carbazoles

Synthetic preparation of carbazoles can be challenging, requiring ring-building strategies and/or precious metal catalysts. Presented herein is a method for the preparation of carbazoles with the use of inexpensive and reliable hypervalent iodine chemistry. An oxidative single-electron-transfer (SET) event initiates cyclization for the preparation of our trifluoromethyl carbazoles. This method has been shown to be useful for a variety of bis(trifluoromethyl)carbazole isomers that are of primary interest for use as battery materials.

A ratiometric fluorescent probe for the rapid and specific detection of HSO3 - in water samples

Hydrosulphite (HSO₃ ^- ), as a common and important chemical reagent, is widely used in everyday life, however excessive use and abuse of HSO₃ ^- can cause potential harmful effects on the environment and in biological health. In this paper, we describe the design and preparation of a colorimetric and ratiometric fluorescence probe for the visual detection of HSO₃ ^- (excitation wavelengths were, respectively, 336 nm and 520 nm). This method showed some advantages including simple preparation, high selectivity, fast response, and significant colour and fluorescence ratio (F₄₅₀ /F₅₉₄ ) changes in the presence of HSO₃ ^- . In addition, this probe was used successfully for the detection of HSO₃ ^- in real water samples and showed a good recovery rate range.

Synthetic ratiometric fluorescent probes for detection of ions

Metal cations and anions are essential for versatile physiological processes. Dysregulation of specific ion levels in living organisms is known to have an adverse effect on normal biological events. Owing to the pathophysiological significance of ions, sensitive and selective methods to detect these species in biological systems are in high demand. Because they can be used in methods for precise and quantitative analysis of ions, organic dye-based ratiometric fluorescent probes have been extensively explored in recent years. In this review, recent advances (2015-2019) made in the development and biological applications of synthetic ratiometric fluorescent probes are described. Particular emphasis is given to organic dye-based ratiometric fluorescent probes that are designed to detect biologically important and relevant ions in cells and living organisms. Also, the fundamental principles associated with the design of ratiometric fluorescent probes and perspectives about how to expand their biological applications are discussed.

Detecting and imaging of SO2 derivatives in living cells with zero cross-talk colorimetric mitochondria-targeted fluorescent probe

It is well known that excessive levels of sulfur dioxide and its derivatives are connected to diverse diseases. Therefore, developing highly sensitive probes to detect and monitor sulfite in living cells is important for the diagnosis of disease and the study of biochemical processes in vivo. In this report, two zero cross-talk ratiometric fluorescent probes were synthesized (CA-ID-MC and CA-BI-MC), which were derived from carbazole-indolenine π-conjugated system for effective detection of sulfite in living cells. Observably, CA-BI-MC exhibited the largest emission shift of 157 nm from 617 to 460 nm with the addition of various concentrations of sulfite, which is beneficial for high-resolution imaging of the sulfite. CA-BI-MC also exhibits high sensitivity and low cytotoxicity. More importantly, this probe successfully located mitochondria and sensed the sulfite in HeLa cells caused by exogenous stimulation.

An effective biocompatible fluorescent probe for bisulfite detection in aqueous solution, living cells, and mice

Sulfur dioxide, an air pollutant, is easily hydrated to sulfites and bisulfites and extremely harmful to human health. On the other hand, endogenous sulfur dioxide is the fourth gasotransmitter. In view of the above, it is worth developing an effective method for the detection of these compounds. In this paper, a novel colorimetric fluorescent probe (Hcy-Mo), based on hemi-cyanine, for bisulfites is reported. Hcy-Mo shows excellent selectivity for bisulfites over various other species including cysteine, glutathione, CN⁻, and HS⁻, and undergoes 1,4-addition reactions at the C-4 atom of the ethylene group. The reaction can be completed in 30 s in a PBS buffer solution and displays high sensitivity (limit of detection is 80 nM) for bisulfites. Test paper experiments show that the probe can be used for bisulfite detection in aqueous solutions. In addition, Hcy-Mo exhibits excellent cell permeability and low cytotoxicity for the successful detection of bisulfites in living MDA-MB-231 cells and in living mice, implying that this probe would be of great benefit to biological researchers for investigating the detailed biological and pharmacological functions of bisulfites in biological systems.

Sulfur dioxide, an air pollutant, is easily hydrated to sulfites and bisulfites and extremely harmful to human health.

Preparation of a Near-Infrared Fluorescent Probe Based on IR-780 for Highly Selective and Sensitive Detection of Bisulfite-Sulfite in Food, Living Cells, and Mice

A near-infrared fluorescent probe was designed and synthesized for the detection of bisulfite-sulfite in food, living HeLa cells, and mice. The probe is a stable hemicyanine skeleton based on IR-780, which produces a distinct color and fluorescence change before and after reaction with bisulfite and shows excellent analytical performance, such as high sensitivity with a detection limit of 0.37 μM and high selectivity toward bisulfite over other substances. More importantly, the probe determined bisulfite in real food samples (crystal sugar and red wine) with superior recoveries (96.7-106.1%) and has been successfully used to monitor bisulfite in living HeLa cells. Notably, the probe was applied to image bisulfite in BALB/c mice in vivo for the first time. Owing to its biocompatibility, this probe provides a desired method to study the metabolism of bisulfite in cells and shows substantial potential usage in other biosystems and in vivo imaging studies.

Pyrazoline-based colorimetric and fluorescent probe for detection of sulphite

This work reports a novel Michael addition based sensor for fluorescence detection of sulphite in river water samples.

A ratiometric fluorescent probe for detection of exogenous mitochondrial SO2 based on a FRET mechanism

A novel imidazo[1,5-a]pyridine-hemicyanine based ratiometric fluorescent probe for detection of mitochondrial SO₂ was designed and synthesized. The probe is based on a fluorescence resonance energy transfer (FRET) mechanism. It exhibits high selectivity and sensitivity towards SO₃²⁻ with a fast response time (3 min) and detection limit of 0.13 μM. Further, it showed low cytotoxicity and was successfully applied to image exogenous mitochondrial SO₂ in cells.

A novel imidazo[1,5-a]pyridine-hemicyanine based ratiometric fluorescent probe for detection of mitochondrial SO₂ was designed and synthesized.

A novel NIR fluorescent probe for the double-site and ratiometric detection of SO2 derivatives and its applications

A “naked-eye” fluorescent probe based on xanthenes was obtained.

Two-Step Sensing, Colorimetric and Ratiometric Fluorescent Probe for Rapid Detection of Bisulfite in Aqueous Solutions and in Living Cells

Bisulfite and sulfite (HSO₃ ^-/SO₃ ^2-) are not only widely used toxic chemicals but also active anions with important biological functions. Hence, the development of new detection methods for HSO₃ ^-/SO₃ ^2- is important for environmental security and human health. In this paper, we report a symmetrical hemicyanine for the detection of HSO₃ ^-/SO₃ ^2-, SHC, which is constructed with p-diphthalaldehyde with trimethylbenzoindolium via condensation. The red fluorescent probe can fast respond to HSO₃ ^-/SO₃ ^2- (<30 s) to give cyan fluorescence, and its sensing process is twice nucleophilic additions, which were observed from fluorescence response, initial ratiometric change, and subsequent turn-on increment; especially in a low-concentration level, the ratiometric fluorescence measurement can eliminate environmental interference. This probe can achieve a quantitative detection of HSO₃ ^-/SO₃ ^2- in a wide concentration range. Furthermore, the probe SHC is a mitochondria-specific probe for ratiometric fluorescent detection of HSO₃ ^-/SO₃ ^2- in living cells.

Design of mitochondria-targeted colorimetric and ratiometric fluorescent probes for rapid detection of SO2 derivatives in living cells

Two mitochondria-targeted colorimetric and ratiometric fluorescent probes for SO₂ derivatives were constructed based on the SO₂ derivatives-triggered Michael addition reaction. The probes exhibit high specificity toward HSO₃^-/SO₃^2- by interrupting their conjugation system resulting in a large ratiometric blue shift of 46-121nm in their emission spectrum. The two well-resolved emission bands can ensure accurate detection of HSO₃^-. The detection limits were calculated to be 1.09 and 1.35μM. Importantly, probe 1 and probe 2 were successfully used to fluorescence ratiometric imaging of endogenous HSO₃^- in BT-474 cells.

A highly selective fluorescent probe for detection of Cd2+ and HSO3− based on photochromic diarylethene with a triazole-bridged coumarin-quinoline group

A novel photochromic diarylethene containing a quinoline-linked 3-aminocoumarin Schiff base unit (1O) was synthesized and used for the selective detection of Cd²⁺ and HSO₃⁻. The synthesized probe exhibited a straightforward response for the selective detection of Cd²⁺. Its fluorescence emission red-shifted ∼126 nm and was enhanced 24.9 fold in the presence of Cd²⁺. Meanwhile, the fluorescence color of 1O changed from dark cyan to golden yellow. The binding stoichiometry between 1O and Cd²⁺ was determined to be 1 : 1. A molecular logic circuit with three inputs and one output was successfully constructed with its light and metal-responsive behaviors. In addition, 1O was able to selectively recognize HSO₃⁻ with a 135-fold enhanced fluorescence emission and a notable fluorescence color change from dark cyan to bright cyan. The ¹H NMR and mass spectrometry analyses suggest that the HSO₃⁻ sensing of 1O is based on the hydrolysis of the Schiff base group of 1O.

A novel photochromic diarylethene containing a quinoline-linked 3-aminocoumarin Schiff base unit (1O) was synthesized and used for the selective detection of Cd²⁺ and HSO₃⁻.

A series of water-soluble A-π-A' typological indolium derivatives with two-photon properties for rapidly detecting HSO3 -/SO3 2- in living cells

It is believed that HSO₃ ^- and SO₃ ^2- play important roles in several physiological processes. However, probes with two-photon absorption to detect HSO₃ ^- or SO₃ ^2- in living cells are still limited. Herein, a series of novel indolium derivatives (L1-L4) with an A-π-A' structure was designed and synthesized as ratiometric probes to detect HSO₃ ^-/SO₃ ^2-in vitro. L3 and L4 display a colorimetric and ratiometric fluorescence dual response to HSO₃ ^-/SO₃ ^2- with a very fast (∼15 s) and high specificity, as well as low detection limits (∼22 nM). Furthermore, their detection is also carried out by using a two-photon excited fluorescence method. A nucleophilic addition reaction is proposed for the sensing mechanism, which is supported by MS, ¹H NMR, and density functional theory (DFT) investigations. Importantly, L3 was successfully used for detecting intrinsically generated intracellular HSO₃ ^-/SO₃ ^2- in cancerous cells under one- and two-photon excited fluorescence imaging.

A novel ratiometric fluorescent probe for selective detection of bisulfite in living cells

In this work, a new type of ratiometric fluorescent probe APCT for bisulfite anion based on Michael-type addition reaction was designed.

A ratiometric fluorescence probe for imaging sulfur dioxide derivatives in the mitochondria of living cells

The fluorescence probe, NBD-Id, was designed and synthesized for the detection of SO₂ derivatives in 100% aqueous solution and living cells.

A simple but effective fluorescent probe for the detection of bisulfite

A simple but effective fluoresecent probe for the detection of bisulfite based on Michael addition reaction.

9H-Carbazole-9-carbaldehyde

The title carbazole derivative, C13H9NO, crystallizes with two independent molecules (AandB) in the asymmetric unit. The dihedral angle between the planar carbazole ring system and the aldehyde group (HC=O) is 3.3 (2)° inAand 7.5 (2)° inB, indicating that the molecules are both nearly planar. In the crystal, theAandBmolecules are linked by a C—H...O hydrogen bond and stack along theb-axis direction. The structure was refined as a two component twin with a refined BASF value of 0.102 (2).

A novel rosamine-based fluorescent probe for bisulfite in aqueous solution

A new rosamine-based fluorescent chemodosimeter has been developed for highly sensitive and selective detection of bisulfite in aqueous solution.

Fluorescent paper sensor fabricated by carbazole-based probes for dual visual detection of Cu2+and gaseous H2S

Cyclically detect Cu²⁺–S²⁻and visual detections of Cu²⁺–H₂S with sensor papers fabricated by carbazole-based fluorescence probe.