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Davis I.,Georgia State University | Liu A.,Georgia State University | Liu A.,Center for Diagnostics and Therapeutics
Expert Review of Neurotherapeutics | Year: 2015

The kynurenine pathway has received increasing attention as its connection to inflammation, the immune system and neurological conditions has become more apparent. It is the primary route for tryptophan catabolism in the liver and the starting point for the synthesis of nicotinamide adenine dinucleotide in mammals. Dysregulation or overactivation of this pathway can lead to immune system activation and accumulation of potentially neurotoxic compounds. These aspects make the kynurenine pathway a promising target for therapeutic development to treat inflammation and disease with neurological aspects, especially in cancer patients undergoing chemotherapy. © Informa UK, Ltd. 2015.

Levitz A.,Georgia State University | Ladani S.T.,Georgia State University | Hamelberg D.,Georgia State University | Hamelberg D.,Center for Diagnostics and Therapeutics | And 2 more authors.
Dyes and Pigments | Year: 2014

Carbocyanine dyes are a class of organic compounds that contain two heterocycles that act as electron donors and acceptors connected by a conjugated methine bridge. Herein the synthesis of a series of 16 novel unsymmetrical trimethine cyanine dyes is reported. Their structures were characterized by various spectroscopic techniques, and their optical properties were measured. Absorption maxima of the dyes were calculated using the time-dependent density-functional theory method and the computational absorption maxima are consistent with the experimental data. The addition of electron withdrawing substituents such as halogens on the heterocycle gave more favorable optical properties such as higher quantum yield and molar absorptivity. The aggregation of these cyanine dyes was studied and compared to a similar series of symmetric cyanine dyes. It was determined that the heterocycle has more effect on aggregation than the side chain and a dye with two different heterocycles will aggregate less than a dye with the same heterocycle. The dyes were also investigated for Lipinski Rule violations as their use is becoming more prevalent for in vivo applications. © 2014 Elsevier Ltd. All rights reserved.

Salim M.M.,Georgia State University | Salim M.M.,Mansoura University | Owens E.A.,Georgia State University | Owens E.A.,Center for Diagnostics and Therapeutics | And 7 more authors.
Analyst | Year: 2014

In this study, a series of new, highly sensitive BF2-chelated tetraarylazadipyrromethane dyes are synthesized and analyzed to be suitable as on/off photo-induced electron transfer modulated fluorescent sensors for determination of intracellular pH. The ethanolic solutions of the new indicators feature absorption maxima in the range of 696-700 nm and a fluorescence emission maximum at 720 nm. Molar absorptivity and fluorescence quantum yield data were determined for the studied set of aza-BODIPY indicators. These indicators have high molar absorption coefficients of ∼80000 M-1 cm-1 and quantum yields (up to 18%). Corresponding pKa values of indicators are determined from absorbance and fluorescence measurements and range from 9.1 to 10.8, depending on the selective positioning of electron-donating functionalities. The excellent photostability of the aza-BODIPY indicators makes them particularly suitable for long duration measurements. The in vitro cellular staining of living tissues in PC3 cells based on the isosbestic point at pH 7.8 and pH 9.3 has been employed which shows an increase in fluorescence intensity at 800 nm with increase in pH for certain compounds and fluorescence intensity decreases at 700 nm. Therefore, the new indicators are suitable for exploitation and adaptation in a diverse range of analytical applications. © the Partner Organisations 2014.

Henary M.,Georgia State University | Henary M.,Center for Diagnostics and Therapeutics | Levitz A.,Georgia State University
Dyes and Pigments | Year: 2013

Carbocyanine dyes are a unique class of organic molecules with high molar extinction coefficients and characteristically long absorption bands with absorption maxima ranging from 500 to 1000 nm making them extremely useful in numerous applications ranging from photography to medicine. Using various synthetic procedures, the conjugated system of these compounds can be modified to yield specific absorption and fluorescence spectra. One way to alter these conjugated systems is to include two different heterocycles thereby producing unsymmetrical dyes. The attractiveness of unsymmetrical carbocyanines has increased significantly over the last decade. For monomethine carbocyanines, there are many methods to synthesize unsymmetrical dyes, but for tri-, penta- and heptamethines the synthesis is more complicated. The synthesis of unsymmetrical carbocyanine dyes is excellent for modifying a dyes absorption wavelength, preparing it for conjugation, or altering the dyes polarity or solubility. The few known unsymmetrical carbocyanine dyes have found use in DNA labeling, dye-sensitized solar cells, and many other applications. There is a great lack of unsymmetrical carbocyanines in the literature and no collective review of them therefore we have put together this review detailing their synthesis and applications. © 2013 Elsevier Ltd. All rights reserved.

Duleepa Pitigala P.K.D.,Georgia State University | Henary M.M.,Georgia State University | Henary M.M.,Center for Diagnostics and Therapeutics | Owens E.A.,Georgia State University | And 4 more authors.
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2016

A solar cell of configuration N-[DDD - - D]-P with a molecularly organized dye J-aggregate [DDD - -D] electronically coupled to n- and p-type semiconductors is illustrated by fabricating a model device with TiO2 and CuSCN as the n- and p-type substrates and the thiocyanate of a cationic pentamethine cyanine dye as D. Functional moieties in D anchors to TiO2 establishing electronic coupling and serving as a template for assembly of a J-aggregated film. Bonding of sulfur in thiocyanate anions at the other end of the aggregate create the electronic coupling needed to facilitates transfer of holes to CuSCN. The cell exhibits photo-response originating from excitons generated in the bulk of the thick dye film as well as direct sensitized injection at the first interface. The dye molecular assembly is found to admit exciton transport over relatively long distances and significant hole mobility. © 2016 Published by Elsevier B.V.

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