• Archives of Pharmacal Research
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• v.19 no.4
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• pp.269-274
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• 1996

The binding interactions between human serum albumin (HSA) and the edible food dyes amaranth, tartrazine and sunset yellow have been studied. Intrinsic association constants and the free energy changes associated with dye-protein binding at physiological pH for amaranth and tartrazine, and at two different pH values for sunset yellow have been calculated from ultrafiltration data. The temperature dependence $(20-40^{\circ}C)$ of the intrinsic association constants at pH 7.4 for amaranth-HSA and tartrazine-HSA mixtures have been measured, from which a plot of the van't Hoff isochore exhibits a marked change in slope around $30^{\circ}C$ indicating a possible change in protein conformation. The number of dye binding sites on HSA is reported for all the above conditions. HSA-ligand binding enthalpies have been used in conjunction with the N-B transitional binding enthalpy for HSA, to calculate the enthalpy for the N-B transition when ligands are bound with the protein.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.89-100
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• 2019

In our previous studies, we developed a ¹⁸F-labeled TSPO-binding ligand, named [¹⁸F]CB251, which has been proved to be a promising TSPO-binding PET radiotracer for the detection and monitoring of TSPO expression in pathological diseases. (Ki = 0.27 nM for TSPO, 1.96% ID/g of tumor uptake at 1h post-injection) Based on these results, we utilized 6,8-dichloro-2-phenylimidazo[1,2-a]pyridineacetamide analogs, CB185 (1) as a targeting moiety for the selective delivery of probes and anticancer molecules to TSPO-overexpressed tissues. In this study, we designed CB185 derivatives contains different PEG chains (n = 1, 3 and 5) and fluorescence dye (Cy5) to identify the necessary space between a TSPO-binding ligand and an anticancer agent. Three CB185 derivatives (11a-c) which contains Cy5 and PEG chain, were synthesized and the effect of PEG additive on their TSPO-binding affinities were evaluated using in vitro assays. The binding affinity for compounds 11a-c was lower than that of PK11195 (Ki = 3.2 nM), but still characterized by nanomolar binding affinity for TSPO (Ki = 46.5 nM for 11a, 51.0 nM for 11b, and 388.5 nM for 11c). These results showed that the conjugates are characterized by a moderate binding affinity toward TSPO except for compound 11c, which PEG chain consist of five PEG monomers. Our finding might add useful information to decide the appropriate PET chain length for developing new TSPO-targeting drug carriers.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2329-2337
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• 2009

Three heteroleptic ruthenium sensitizers, Ru(L)($L^1)(NCS)_2$ [L = 4,4'-dicarboxylic acid-2,2'-bipyridine, Ru-T1: $L^1$ = (E)-2-(4'-methyl-2,2'-bipyridin-4-yl)-3-(thiophen-2-yl)acrylonitrile, Ru-T2: $L^2$ = (E)-3-(5'-hexyl-2,2'-bithiophen-5- yl)-2-(4'-methyl-2,2'-bipyridin-4-yl)acrylonitrile, and Ru-T3: $L^3$ = (E)-3-(5"-hexyl-2,2':5',2"-terthiophen-5-yl)-2- (4'-methyl-2,2'-bipyridin-4-yl)acrylonitrile)], were synthesized and used as photosensitizers in nanocrystalline dyesensitized solar cells (DSSCs). The introduction of the 3-(5-hexyloligothiophen-5-yl)acrylonitrile group increased the conjugation length of the bipyridine donor ligand and thus improved their molar absorption coefficient and light harvesting efficiency. DSSCs with the configuration of Sn$O_2$: F/Ti$O_2$/ruthenium dye/liquid electrolyte/Pt devices were fabricated using these Ru-$T1{\sim}T3$ as a photosensitizers. Among the devices, the DSSCs composed of Ru-T2 exhibited highest power conversion efficiency (PCE) of 2.84% under AM 1.5 G illumination (100 mW/$cm^2$).

• Journal of the Korean Applied Science and Technology
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• v.22 no.4
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• pp.299-305
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• 2005

In this study, we designed color of tunable and high efficient organic materials using the quantum dynamics and the semi-empirical calculation, and applied this results to the fabrication of organic light-emitting diodes. Also we optimized the molecular structure of phosphorescent materials and the energy transfer from a host to a dye which makes organic light-emitting diodes improve. Using quantum dynamics method, the molecular structures of ligand only and the whole metal chelate were optimized, and these energy levels were calculated. From this test results, we could understand the emission mechanism of phosphors with various ligands as well as design the proper ligands reducing the T-T annihilation and the carrier lifetime. We also could design ligands with various colors using this test method.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.43-48
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• 2017

Chemotherapy, radiation therapy, and surgery are major methods to treat cancer. However, current cancer treatments report severe side effects and high recurrences. Recent studies about engineering nanoparticles as a drug carrier suggest possibilities in terms of specific targeting and spatiotemporal release of drugs. While many nanoparticles demonstrate lower toxicity and better targeting results than free drugs, they still need to improve their performance dramatically in terms of targeting accuracy, immune responses, and non-specific accumulation at organs. One possible way to overcome the challenges is to make precisely controlled nanoparticles with respect to size, shape, surface properties, and mechanical stiffness. Here, we demonstrate $500{\times}200nm$ discoidal polymeric nanoconstructs (DPNs) as a drug delivery carrier. DPNs were prepared by using a top-down fabrication method that we previously reported to control shape as well as size. Moreover, DPNs have multiple payloads, poly lactic-co-glycolic acid (PLGA), polyethylene glycol (PEG), lipid-Rhodamine B dye (RhB) and Salinomycin. In this study, we demonstrated a potential of DPNs as a drug carrier to treat cancer.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.285-295
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• 1999

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays. They are attractive because of their capability of multi-color emission, and low operation voltage. An approach to realize such device characteristics is to use active layers of lanthanide complexes with their inherent extremely sharp emission bands in stead of commonly known organic dyes. In general, organic molecular compounds show emission due to their $\pi$-$\pi*$ transitions resulting in luminescence bandwidths of about 80 to 100nm. Spin statistic estimations lead to an internal quantum efficiency of dye-based EL devices limited to 25%. On the contrary, the fluorescence of lanthanide complexes is based on an intramolecular energy transfer from the triplet of the organic ligand to the 4f energy states of the ion. Therefore, theoretical internal quantum efficiency is principally not limited. In this study, Powders of TPD, $Eu(TTA)_3(phen) and AlQ_3$ in a boat were subsequently heated to their sublimation temperatures to obtain the growth rates of 0.2~0.3nm/s. Organic electrolumnescent devices(OELD) with a structure of $glass substrate/ITO/Eu(TTA)_3(phen)/AI, glass substrate/ITO/TPD/Eu(TTA)_3(phen)/AI and glass substrate/ITO/TPD/Eu(TTA)_3(phen)/AIQ_3AI$ structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, $Eu(TTA)_3(phen)$ as an emitting material, and Tris(8-hydroxyquinoline)Aluminum$(AlQ_3)$ as an electron transporting layer. Electroluminescent(EL) and current density-voltage(J-V) characteristics of these OELDs with various thickness of $Eu(TTA)_3(phen)$ layer were investigated. The triple-layer structure devices show the red EL spectrum at the wavelength of 613nm, which is almost the same as the photoluminescent(PL) spectrum of $Eu(TTA)_3(phen)$.It was found from the J-V characteristics of these devices that the current density is not dependent on the applied field, but on the electric field.