Joung Hae Lee

Cu2+-Induced Intermolecular Static Excimer Formation of Pyrenealkylamine

Synthesis of monopyrenylalkylamine derivative 1 and its fluorescence behavior for Cu2+ in H2O/CH3CN (1:1, v/v) were investigated. Upon Cu2+ binding, 1, bearing a sulfonamide group, exhibited a marked excimer emission at 455 nm along with a weak monomer emission at 375 nm. The excimer emission, driven by formation of an intermolecular pyrenyl static excimer upon Cu2+ binding to the sulfonamide group, is rationalized by experimental and theoretical DFT calculation results.

Molecular modulated cysteine-selective fluorescent probe.

We have synthesized a series of coumarins (1-3) that can emit fluorescence in a turn-on manner through a Michael-type reaction with thiol-containing compounds. The only difference among the coumarins is the position of a carboxyl group on its benzene ring moiety near the double-bond conjugated coumarin. Their selectivity for Cys, GSH, and Hcy as well as the associated fluorogenic mechanism were illustrated by fluorescence spectroscopy, DFT calculations, and kinetic studies. All isomers prefer Cys over GSH in the reaction from 48.6 (probe 3) to 111-fold (probe 1) as demonstrated in a second order kinetics. The high selectivity of probe 1 to Cys might be achieved since the ortho carboxyl group on its benzene ring prefers a less negatively charged nucleophile. During intracellular Cys detection using 1, a possible interference by a large amount of GSH in the HepG2 cells was evaluated. The cells were treated with l-buthionine sulfoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase, providing an experimental condition where the cells could not synthesize GSH from Cys or other species. Then, the fluorescence intensity of 1 in HepG2 cells under BSO-H(2)O(2) treatment was strongly enhanced by N-acetylcysteine (NAC), a precursor of Cys, implicating that the fluorescence signal from the cells is mainly associated with changes in intracellular [Cys] rather than that in intracellular [GSH].

Rational design of biotin–disulfide–coumarin conjugates: a cancer targeted thiol probe and bioimaging

Biotin-disulfide-coumarin conjugates are designed and synthesized as novel fluorescent sensors for cancer targeted intracellular thiol imaging in living organisms. In vitro experiments disclose that probe 6 is preferentially taken up by biotin receptor-positive A549 tumor cells through receptor mediated endocytosis.

Metal ion complexation by acyclic polyethers with lipophilic amide, thioamide, and amine end groups

A series of acyclic polyethers with lipophilic amide, thioamide, and amine end groups was synthesized. Metal ion transport across bulk liquid membranes and measurement of thermodynamic parameters for ligand-metal ion complexation by titration calorimetry show strong selectivity for complexation of lead ion over other metal ion species for the diamide ligand. Lead ion complexation by the acyclic polyether diamide involves the amide oxygens and silver ion coordination by a dithioamide analog involves the thioamide sulfurs. With a proper length of the ethereal linkage, the ligand wraps around the metal ion in a pseudocyclic fashion.

Lead selective lipophilic acyclic diionizable polyethers.

A structural series of acyclic polyether dicarboxylic acids with n-butyl and n-tetradecyl alkyl side chains at the alpha-position of the carboxylic acid units, as well as varying lengths of the ethylene glycol ether linkage connecting two benzo units were prepared. In terms of stability constants, competitive solvent extraction and cation transport experiment by bulk liquid membrane toward transition metal ions, ligand 3 with a monoethylene glycol unit and n-butyl side chains provide the best selectivity for the lead ion.

DETERMINATION OF TRACE AND TOXIC ELEMENTS IN KOREAN RICE CRM BY INAA, ICP AND AAS

Trace and toxic elements in Certified Reference Material (CRM) made of Korean rice at the Korea Research Institute of Standards and Science have been analyzed by Instrumental Neutron Activation Analysis (INAA). Data intercomparison from the measurement with those of Atomic Absorption Spectrometry (AAS) and Induced Coupled Plasma Spectrometry (ICPS) has been studied. The powdered samples were sterilized at 1.5·106 rad in the bottles using a60Co source after sieving and spiking to specific elements such as As, Cd, Cr, Cu and Hg and then the homogeneity of samples was assessed. Rice flour (SRM 1568a) and standard solutions made by the National Institute of Standards Technology (NIST) were used to construct the calibration curves for the INAA and the chemical methods, respectively. The uncertainties and concentration of constituent elements were determined and the possibility of their use for analytical quality control was considered.

Real time OFF–ON monitoring of gluthathione (GSH) in living cell

A simple chemodosimetric probe (1) is reported which detects Glutathione (GSH) selectively over other relevant biological species under physiological condition by turning on its fluorescence through the imine hydrolysis reaction. The probe has also been used for imaging of GSH in the live cells by confocal microscopy.Graphical AbstractThis report discloses pyrene-based chemodosimetric probe which exhibit a selective response toward Glutathione (GSH) over other biological thiols and was successfully applied to the imaging of GSH in living cells.

Thermal Model and Optimization of a Large Crystal Detector using a Metallic Magnetic Calorimeter

We established a simple thermal model of the heat flow in a large crystal detector designed for a neutrinoless double beta decay experiment. The detector is composed of a CaMoO

Roles of chemical metrology in electronics industry and associated environment in Korea: A tutorial

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