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[Display omitted] • A lysosome-targetable fluorescent probe for H 2 O 2 has been reported. • The probe displays high sensitivity and high selectivity for H 2 O 2. • The probe can be utilized for determination of H 2 O 2 within the lysosomes of living cells. As an important member of reactive oxygen species, hydrogen peroxide (H 2 O 2) plays a key role in oxidative stress and cell signaling. Abnormal levels of H 2 O 2 in lysosomes can induce damage or even loss of lysosomal function, leading to certain diseases. Therefore, real-time monitoring of H 2 O 2 in lysosomes is very important. In this work, we designed and synthesized a novel lysosome-targeted fluorescent probe for H 2 O 2 -specific detection based on a benzothiazole derivative. A morpholine group was used as a lysosome-targeted unit and a boric acid ester was chosen as the reaction site. In the absence of H 2 O 2 , the probe exhibited very weak fluorescence. In the presence of H 2 O 2 , the probe showed an increased fluorescence emission. The fluorescence intensity of the probe for H 2 O 2 displayed a good linear relationship in the concentration range of H 2 O 2 from 8.0 × 10−7 to 2.0 × 10−4 mol·L−1. The detection limit was estimated to be 4.6 × 10−7 mol·L−1 for H 2 O 2. The probe possessed high selectivity, good sensitivity and short response time for the detection of H 2 O 2. Moreover, the probe had almost no cytotoxicity and had been successfully applied to confocal imaging of H 2 O 2 in lysosomes of A549 cells. These results illustrated that the developed fluorescent probe in this study could provide a good tool for the determination of H 2 O 2 in lysosomes. [ABSTRACT FROM AUTHOR]

The reactive nitrogen species (RNS) in lysosomes play a major role during the regulation of lysosomal microenvironment. Nitroxyl (HNO) belongs to active nitrogen species (RNS) and is becoming a potential diagnostic and therapeutic biomarker. However, the complex synthesis routes of HNO in biosystem always hinder the exact determination of HNO in living cells. Here, a rhodamine-based fluorescent probe used to determine nitroxyl (HNO) in lysosomes was constructed and synthesized. 2-(Diphenylphosphino)benzoate was utilized as the sensing unit for HNO and morpholine was chose as the targeting group for lysosome. Before the addition of HNO, the probe displayed a spirolactone structure and almost no fluorescence was found. After the addition of HNO, the probe existed as a conjugated xanthene form and an intense green fluorescence was observed. The fluorescent probe possessed fast response (3 min) and high selectivity for HNO. Furthermore, fluorescence intensity of the probe linearly related with the HNO concentration in the range of 6.0 × 10 -8 to 6.0 × 10 -5  mol L -1 . The detection limit was found to be 1.87 × 10 -8  mol L -1 for HNO. Moreover, the probe could selectively targeted lysosome with excellent biocompatibility and had been effectually utilized to recognize exogenous HNO in A549 cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Nitroxyl (HNO) is an important reactive nitrogen that is associated with various states in physiology and pathology and plays a unique function in living systems. So, it is important to exploit fluorescent probes with high sensitivity and selectivity for sensing HNO. In this paper, a novel ratiometric fluorescent probe for HNO was developed utilizing intramolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET) mechanisms. The probe selected coumarin as energy donor, naphthalimide as energy receptor and 2-(diphenylphosphino)benzoate as the sensing site for detecting HNO. When HNO was not present, the 2-(diphenylphosphino)benzoate unit of the probe restricted electron transfer and the ICT process could not occur, leading to the inhibition of FRET process as well. Thus, in the absence of HNO the probe displayed the intrinsic blue fluorescence of coumarin. When HNO was added, the HNO reacted with the 2-(diphenylphosphino)benzoate unit of the probe to yield a hydroxyl group which resulting in the opening of ICT process and the occurring of FRET process. Thus, after providing HNO the probe displayed yellow fluorescence. In addition, the probe showed good linearity in the ratio of fluorescence intensity at 545 nm and 472 nm (I 545 nm /I 472 nm ) with a concentration of HNO (0.1-20 μM). The probe processed a detection limit of 0.014 μM and a response time of 4 min. The probe also specifically identified HNO over a wide pH scope (pH = 4.00-10.00), including physiological conditions. Cellular experiments had shown that this fluorescent probe was virtually non-cytotoxic and could be applied for ratiometric sensing of HNO in A549 cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

As a high reactive oxygen species (ROS) and a reactive nitrogen species (RNS), peroxynitrite anion (ONOO - ) is widely present in organisms and plays influential roles in physiological and pathological processes. It is of great significance to develop effective fluorescent probes for imaging peroxynitrite variation in living systems. Herein we present a novel fluorescent probe TQC0 for monitoring ONOO - based on the iminocoumarin platform, and this probe was synthesized by the knoevenagel condensation between a dihydropyridine-salicylaldehyde derivative and 2-benzothiazole-acetonitrile, and subsequently masked with the boronate moiety. The obtained probe TQC0 exhibited a high signal-to-noise ratio (206-fold) and a quick 'turn-on' response (about 10 min) with great selectivity and sensitivity. Furthermore, the probe TQC0 was successfully applied for imaging ONOO - in living cells with low cytotoxicity., (© 2024 John Wiley & Sons Ltd.)

A three-component strategy was developed for 3-phenyl-9 H -imidazo[1,5- a ]indol-9-one preparation from indole-2-carboxaldehydes, aromatic aldehydes, and ammonium acetate under copper catalysis conditions. In this process, a new five-membered ring was formed and the C3 position in the indole substrate was selectively oxidized into a ketone skeleton using oxygen as the sole oxidant and ammonium acetate as the nitrogen source. Furthermore, same products also could be achieved from indole-2-carboxaldehydes and benzyl amines under similar reaction conditions.

A metal-free method for the construction of 2-substituted quinolines and benzo[ f ]quinolines from aromatic amines, aldehydes, and tertiary amines has been demonstrated. Cheap and readily available tertiary amines acted as the vinyl source. A new pyridine ring was selectively formed via [4 + 2] condensation that was promoted by ammonium salt under neutral conditions and an oxygen atmosphere. This strategy provided a new route for the preparation of various quinoline derivatives with different substituents at the pyridine ring, which provides the possibility of further modification.

A CuBr 2 -catalyzed annulation of 2-bromo- N -arylbenzimidamide with selenium/sulfur powder for the synthesis of benzo[ d ]isoselenazole and benzo[ d ]isothiazole in generally good yields was investigated. This synthetic strategy features good substrate scope and functional group tolerance. Furthermore, the corresponding products could be converted into N -aryl indoles via rhodium III -catalyzed ortho C-H activation of the N -phenyl ring, providing an efficient approach for axial aromatic molecules.

A Pd-catalyzed C-O cross-coupling of O -acyl hydroxylamines and tertiary or secondary alkyl electrophiles was reported without the cleavage of the rather fragile N-O bond. The described strategy provides direct access to congested N , N , O -trisubstituted hydroxylamines bearing an α-quaternary carbon center under mild conditions in high yields and features exclusively chemoselective C-O bond formation, a broad substrate scope, and excellent functional group tolerance. The synthetic potential of the cross-coupling was established via pharmaceuticals derivatizations and a series of postcatalytic modifications.

A simple and high-throughput colorimetric analysis array has been constructed for quantifying H 2 O 2 in milk using Fe 3 O 4 quantum dots (QDs), which were coated with sodium alginate (SA) and chromogenic substrate onto the arrayed capillary tubes. It was discovered that the Fe 3 O 4 QDs could present larger peroxidase-like catalysis than Fe 3 O 4 nanoparticles (NPs). Particularly, dramatically enhanced catalysis activity could be achieved for Fe 3 O 4 QDs if coated with SA films. Moreover, the use of SA could protect Fe 3 O 4 QDs to expect the improved environmental stability. A capillary arrays-based high-throughput colorimetric platform was thereby developed for the detection of H 2 O 2 in milk, with levels linearly ranging from 10 to 400 μM. Importantly, the developed colorimetric platform with the capillarity power for automatic fetching of multiple samples may promise the practical applications for extensive monitoring of multiple H 2 O 2 samples for food safety., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A novel strategy for the preparation of functional carbazoles through NaI-catalyzed formal [4 + 2] annulation of 2-(indol-3-yl)cyclohexanones and alkynes/alkenes has been developed. The present approach started from easily available raw materials and provided a variety of tetrahydrobenzo[ c ]carbazolones in satisfactory yields under metal- and solvent-free conditions. Furthermore, the products could be further transformed into structurally valuable carbazole-based conjugated derivatives.

A high-throughput and selective fluorimetric platform has been constructed for the analysis of ammonia in blood by using a polymer-stabilized metal-organic framework (MOF) of porous NH2-MIL-125, which was coated onto a wettable microwells array constructed on an indium tin oxide (ITO) substrate. It was found that the nitrogen plasma treatment for the ITO substrate could create a super-hydrophilic interface that combined with the hydrophobic pattern yielded a wettable microwells array, enabling the condensation-based enrichment of targets from the sample droplets. Moreover, the NH2-MIL-125 MOF encapsulated using polymers could be firmly coated onto the microwells to act as fluorescent probes for sensing NH3 with enhanced responses. In addition, the use of the polymer polyvinyl pyrrolidone could protect and stabilize the crystals of NH2-MIL-125 probe in aqueous media, revealing the improved hydrophilicity and significantly depressed signal background. The as-developed fluorimetric platform, containing a MOF-coated microwells array, can enable the detection of ammonia in blood, with concentrations ranging linearly from 0.10 to 300 μM. More importantly, this plasma treatment-based fabrication route may hold promise for designing different wettable microwells arrays for the high-throughput detection of multiple targets in the fields of biomedical analysis and environmental monitoring.