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A new ratiometric fluorescent probe ( E )-2-(benzo[ d ]thiazol-2-yl)-3-(8-methoxyquinolin-2-yl)acrylonitrile (HQCN) was synthesised by the perfect blending of quinoline and a 2-benzothiazoleacetonitrile unit. In a mixed aqueous solution, HQCN reacts with hydrazine (N 2 H 4 ) to give a new product 2-(hydrazonomethyl)-8-methoxyquinoline along with the liberation of the 2-benzothiazoleacetonitrile moiety. In contrast, the reaction of hypochlorite ions (OCl - ) with the probe gives 8-methoxyquinoline-2-carbaldehyde. In both cases, the chemodosimetric approaches of hydrazine and hypochlorite selectively occur at the olefinic carbon but give two different products with two different outputs, as observed from the fluorescence study exhibiting signals at 455 nm and 500 nm for hydrazine and hypochlorite, respectively. A UV-vis spectroscopy study also depicts a distinct change in the spectrum of HQCN in the presence of hydrazine and hypochlorite. The hydrazinolysis of HQCN exhibits a prominent chromogenic as well as ratiometric fluorescence change with a 165 nm left-shift in the fluorescence spectrum. Similarly, the probe in hand (HQCN) can selectively detect hypochlorite in a ratiometric manner with a shift of 120 nm, as observed from the fluorescence emission spectra. HQCN can detect hydrazine and OCl - as low as 2.25 × 10 -8 M and 3.46 × 10 -8 M, respectively, as evaluated from the fluorescence experiments again. The excited state behaviour of the probe HQCN and the chemodosimetric products with hydrazine and hypochlorite are studied by the nanosecond time-resolved fluorescence technique. Computational studies (DFT and TDDFT) with the probe and the hydrazine and hypochlorite products were also performed. The observations made in the fluorescence imaging studies with human blood cells manifest that HQCN can be employed to monitor hydrazine and OCl - in human peripheral blood mononuclear cells (PBMCs). It is indeed a rare case that the single probe HQCN is found to be successfully able to detect hydrazine and hypochlorite in PBMCs, with two different outputs.

Background: Oxidative stress is common in type 2 diabetes. It is characterised by increased levels of reactive oxygen species (ROS), of which hypochlorous acid (HOCl) is an important component. Type 2 diabetes is characterised not only by hyperglycemia, but also by dyslipidemia. It probably underlies both the development of diabetes and also resulting complications, like cardiovascular disease. We applied a novel fluoroprobe RHQ to estimate endogenous HOCl and myeloperoxidase (MPO) activity in diabetes and dyslipidemia., Methods: Our newly designed probe, RHQ (rhodamine-quinoline based chemodosimeter) is capable of estimating endogenous HOCl selectively out of the ROS components. Isolated leukocytes from study subjects were treated with DCFDA and monocytes and neutrophils with RHQ for estimating endogenous ROS and HOCl respectively. Plasma AOPP, an indicator of HOCl was also measured. We attempted to find out the key reasons of higher HOCl content in diabetic dyslipidemic subjects by quantitating endogenous hydrogen peroxide (H2O2) and myeloperoxidase (MPO) activity., Results: Isolated PBMCs from diabetic dyslipidemic subjects indicated enhanced ROS and HOCl generation followed by diabetic subjects without dyslipidemia and healthy controls. We explored increased production of H2O2 and enhanced enzymatic activity of myeloperoxidase (MPO) among diabetic dyslipidemic subjects (p<0.0001) resulting in higher HOCl content., Conclusion: The hyperglycemic and hyperlipidemic challenges together enhance the production of HOCl and the fluoroprobe RHQ may be used as a novel diagnostic marker to evaluate the extent of this toxicity., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A new visible-light-excitable fluorescence ratiometric probe for OCl(-) has been developed based on a triphenylamine-diamiomaleonitrile (TAM) moiety. The structure of the dye was confirmed by single-crystal X-ray analysis. It behaves as a highly selective and sensitive probe for OCl(-) over other analytes with a fast response time (∼100 s). OCl(-) reacts with the probe leading to the formation of the corresponding aldehyde in a mixed-aqueous system. The detection limit of the probe is in the 10(-8) M range. The probe (TAM) also exhibits solvatofluorochromism. Changing the solvent from non-polar to polar, the emission band of TAM largely red-shifted. Moreover, the probe shows an excellent performance in real-life application in detecting OCl(-) in human blood cells. The experimentally observed changes in the structure and electronic properties of the probe after reaction with OCl(-) were studied by DFT and TDDFT computational calculations., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)