Determination of thiol by high-performance liquid chromatography and fluorescence detection with 5-methyl-(2-(<Emphasis Type="Italic">m</Emphasis>-iodoacetylaminophenyl)benzoxazole

A new high-performance liquid chromatographic (HPLC) method for measuring low molecular weight (LMW) thiol-containing compounds, including cysteine (CysH), glutathione (GSH), N-acetylcysteine (Nac), penicillamine (PA), and 2-mercaptoethanol (2-ME), has been developed by using 5-methyl-(2-(m-iodoacetylaminophenyl)benzoxazole (MIPBO) as fluorescence-labeling reagent. The derivatization and separation conditions have been investigated in detail. Detection limits ranging from 3.5 to 15.0 fmol were achieved for the thiols investigated in a 16 min separation with detection wavelengths 310 and 375 nm for the excitation and emission, respectively. The utility of the proposed method has been validated by measuring CysH in human urine samples.     

Cu(phen)2+2和Cu(bpy)2+2与6-巯基嘌呤、腺嘌呤相互作用的研究

在ｐＨ为７．０的磷酸盐缓冲溶液中，用荧光光谱、紫外光谱、电化学及紫外光谱电化学等方法研究了铜配合物与６－巯基嘌呤、腺嘌呤的相互作用．结果表明，Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤发生了相互作用，但作用程度不同．根据荧光光谱实验数据计算出Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤的配位比均为１∶１；它们与６－巯基嘌呤作用的配位常数分别为２．２３×１０４Ｌ／ｍｏｌ和６．１１×１０４Ｌ／ｍｏｌ；与腺嘌呤作用的配位常数分别为１．９５×１０４Ｌ／ｍｏｌ和５．１２×１０４Ｌ／ｍｏｌ．电化学实验也获得了相近的结果．这为解释Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与ＤＮＡ的作用机理及作用部位提供了有益的信息     

Chiral imides as potential chiroptical switches: synthesis and optical properties

A series of chiral aromatic imides and diimides were synthesized and their electrochemical, absorption, fluorescent, and chiroptical properties were examined for their potential application as molecular chiroptical switches. These compounds exhibit strong UV-vis absorptions, and can be electrochemically reduced to radical anions that absorb in the near infrared (NIR) region. Further reduction to the dianionic states results in new absorptions in the visible region. The changes in circular dichroism upon redox switching were apparent in the UV-vis region but were absent in the NIR region.     

Recent progress in two-photon small molecule fluorescent probes for enzymes

This review aims to provide a summary of the progress in TP small molecule fluorescent probes for enzymes in recent years and displays the main fluorescent mechanisms that have been applied to design probes.     

薄膜荧光传感器研究进展

按薄膜荧光传感器的制备方法, 从物理薄膜、化学薄膜和自组装单层膜等三个方面综述了近年来薄膜荧光传感器的研究进展. 在此基础上, 展望了薄膜荧光传感器的研究前景.     

Group 6 tetracarbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene: Spectral characterization,electrochemistry, solvatochromism and photophysical studies

A new series of group 6 carbonyl complexes of N-[(2-pyridyl)methyliden]-α (or β)-aminonaphthalene (α/β-NaiPy) are described in this work. The complexes are formulated as cis-[M(CO)₄(α/β-NaiPy)] by elemental, mass and other spectroscopic data. The complexes show emission spectra at room temperature and their quantum yield lies between 0.4 and 0.5. All the complexes exhibit negative solvatochromism. Cyclic voltammetry shows metal centred oxidation and ligand reductions.     

Fluorimetric assay for measuring Dns-His-Lys-Arg-His-Lys cleaving enzyme using high-performance liquid chromatography

A rapid and sensitive assay for the determination of Dns-His-Lys-Arg-His-Lys cleaving enzyme activity is reported. This assay is based on fluorimetric detection of a dansylated dipeptide, 5-dimethylaminonaphthalene-1-sulfonyl-His-Lys, enzymatically formed from the substrate 5-dimethylaminonaphthalene-1-sulfonyl-His-Lys-Arg-His-d-Lys, after separation by high-performance liquid chromatography (HPLC) using a C-18 reversed-phase column by isocratic elution. This assay is sensitive enough to measure 5-dimethylaminonaphthalene-1-sulfonyl-His-Lys at concentrations as low as 7 pmol, and yields highly reproducible results and requires less than 9.0 min per sample for separation and quantitation. The optimum pH for Dns-His-Lys-Arg-His-Lys cleaving enzyme activity was 7.5-8.0. The Michaelis constant (K_m) and the maximum velocity (V_max) values were 33.3 μM and 47.07 pmol/(μg h), respectively with the use of enzyme extract obtained from bovine pituitary. By using this assay, axonal transport of this enzyme activity was observed 48 h after double ligations of rat sciatic nerves. The high sensitivity and selectivity of this assay would be useful for clarification of the physiological role of this enzyme.     

Optical CO(2) sensor of the combination of colorimetric change of alpha-naphtholphthalein in poly(isobutyl methacrylate) and fluorescent porphyrin in polystyrene

An optical CO₂ sensor based on the overlay of the CO₂ induced absorbance change of pH indicator dye α-naphtholphthalein in poly(isobutyl methacrylate) (polyIBM) layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO₂ concentration. The ratio I₁₀₀/I₀ value of the sensing film consisting of α-naphtholphthalein in polyIBM and TPP in polystyrene layer, where I₀ and I₁₀₀ represent the detected luminescence intensities from a layer exposed to argon and CO₂ saturated conditions, respectively, that the sensitivity of the sensor, is estimated to be 192. The response and recovery times of the sensing film are less than 6.0 s for switching from argon to CO₂, and for switching from CO₂ to argon. The signal changes are fully reversible and no hysterisis is observed during the measurements. The highly sensitive optical CO₂ sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein in polyIBM layer with CO₂ is achieved.     

Derivatization of carboxylic acids with 9-bromomethylacridine using micellar phase-transfer catalysis

Summary Micellar phase-transfer catalysis (MPTC) offers the opportunity to derivatize carboxylic acids directly in an aqueous matrix without prior extraction of the acids into a suitable aprotic solvent. The currently developed MPTC system consists of a non-ionic surfactant, Arkopal N-130, an ion-pair agent, tetrakis-(decyl)-ammonium bromide, and a novel fluorescence reagent, 9-bromomethylacridine. The MPTC system can be applied to the derivatization of many types of carboxylic acids. The reaction rate is affected by the lipophilicity of the acid and by the presence of other functional groups. For lipophilic carboxylic acids the reaction is complete within 5 min at 60°C and pH 7.0.     

NaBr对C12-s-C12•2Br/氯仿体系中反胶团增溶水能力的影响

近红外(NIR)光谱技术可用于表征氯仿体系中反胶团增溶水的能力. 对于C12-s-C12•2Br (s=2, 3, 4, 5, 6, 8)系列, 不论体系是否含有NaBr电解质, 由于具有较短联接链的表面活性剂易形成较大的反胶团, 其增溶水的能力随着联接链长度增加而降低. 与未含NaBr电解质的体系相比, 当体系中存在NaBr电解质时所形成的反胶团增溶水能力降低.