A coumarin-based fluorescent turn-on probe for detection of biothiols in vitro

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.

Hydrogen-bond-driven supramolecular helical assembly of a coumarin-substituted phthalonitrile derivative: synthesis and in vitro anticancer activity against colorectal adenocarcinoma

Phthalonitrile derivatives are generally reported to crystallize in space groups P21/c and P 1 in the literature. In this study, 7-hydroxy-4,8-dimethyl-3-pentylcoumarin (2) and its phthalonitrile derivative (2d) were crystallized; 2d crystallized in the rare trigonal space group R 3. In the phthalonitrile derivative (2d), weak C—H...O hydrogen-bonding interactions promoted the formation of supramolecular double helices, and these supramolecular P and M double helices came together to form a honeycomb-like architectural motif involving one-dimensional tubular channels. In silico molecular-docking studies were performed to support the experimental processes and the results agree with each other. In vitro studies of compounds 2 and 2d were performed in LoVo colorectal adenocarcinoma and CCD18Co healthy human cell lines using flow cytometry. For compounds 2 and 2d, there was a statistically significant increase (p < 0.001) in both early and late apoptosis with respect to the control in a dose-dependent manner.

Pyranopyrazole based Schiff base for rapid colorimetric detection of arginine in aqueous and real samples

A novel pyranopyrazole-based Schiff base PPS has been synthesized via a condensation reaction between aldehyde and hydrazide derivatives of pyranopyrazole.

Two-photon fluorescent turn-on probes for highly efficient detection and profiling of thiols in live cells and tissues

Thiols are important units in amino acids such as cysteine and peptides like glutathione. Development of chemical sensors capable of precise detection of thiols is important in cancer diagnosis and therapy. We have developed novel two-photon fluorescent turn-on probes for selective detection of thiols. The probes displayed excellent sensitivity and low detection limits. The dual-purpose probes have been demonstrated to be suitable for simultaneous imaging and proteome profiling in live cells and tumor tissues. The unique turn-on design endows the probes with excellent selectivity toward thiols in vitro and in situ, and can be further developed to support a thiol-quantification assay.

Fe(III) bipyridyl or phenanthroline complexes with oxidase-like activity for sensitive colorimetric detection of glutathione

In this study, three types of Fe(III) bipyridyl or phenanthroline (Fe(III)-L₃ ) complex could directly catalyze 3,3',5,5'-tetramethylbenzidine (TMB) to induce blue chromogenic changes without H₂ O₂ . Fe(III)-L₃ complex could induce a colour change in TMB directly after a short incubation time. Due to the high oxidase-like activity of the Fe(III)-L₃ complexes, superoxide anion radicals (O₂ ^•- ) were formed in solution. Intermediates radical involving oxo-iron species were then produced that oxidized TMB to its oxidation products (oxTMB), which had an absorbance maximum at 652 nm. Glutathione (GSH) could inhibit the oxidation reaction of the Fe(III)-L₃ complex-TMB system, a rapidly colorimetric method was established for the specific detection of GSH that had a detection limit of 0.1 μM. Furthermore, Fe(III)-L₃ complexes could catalyze TMB to oxTMB directly without H₂ O₂ . This fast and simple colorimetric method may open a new avenue for application in the point-of-care diagnosis field using the TMB chromogenic system.

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.

A new fluorescent probe for sensing of biothiols and screening of acetylcholinesterase inhibitors

An axial N₂O-type BODIPY probe has been proposed for sensitive and selective sensing of biothiols and screening of AChE inhibitors using a fluorescence turn-on assay.

Structurally regular arrangement induced fluorescence enhancement and specific recognition for glutathione of a pyrene chalcone derivative

Glutathione (GSH) is an important antioxygen and free radical scavenger in the organism. Level of GSH in vivo is associated with many diseases and specific recognition for GSH is very important. Here, a pyrene chalcone derivative 1 1-(2-hydroxyphenyl)-3-(1-pyrenyl)-2-propen-1-one as specific probe for GSH was developed. The probe can give rise to rapid blue fluorescence enhancement for GSH based on Michael addition reaction in pure PBS solution with high sensitivity, fast response rate and high specificity. The compound also can be applied for GSH detection in HeLa cell. Simultaneously, the compound exhibits blue fluorescence emission enhancement in methanol-water (1:1, v/v) solution with fluorescence quantum yield being 0.45 due to the competition of water molecules for hydrogen bonds between hydroxyl and carbonyl and the formation of structurally regular rodlike crystals, which allows regulating fluorescence emission by different solvent condition.

Coumarin-Based Small-Molecule Fluorescent Chemosensors

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

Nitroolefin-modified cyclometalated iridium(iii) complexes for tunable detection of biothiols with deep-red emission

Two nitroolefin-modified cyclometalated iridium(iii) complexes were employed as turn-on probes for the rapid (1 min) detection of biothiols with tunable emission.

Facile Synthesis and Fluorescent Properties of Two Novel 4-Aryl-2,6-Dicoumarinylpyridines

Two novel 4-aryl-2,6-dicoumarinylpyridines were synthesised in the presence of tetrabutylammonium hydrogen sulphate via a one-pot reaction. In addition, the absorption and fluorescence spectra of the synthesised compounds in chloroform were measured for the first time.

Synthesis and Fluorescent Properties of Coumarin–Chalcone Hybrids

Four coumarin–chalcone hybrids were synthesised utilising condensation of acetylcoumarin with three benzaldehydes and cinnamaldehyde, respectively. Moreover, the absorption and fluorescence spectra of these synthesised compounds in dichloromethane were measured.