Polydiacetylene‐Based Colorimetric Self‐Assembled Vesicular Receptors for Biological Phosphate Ion Recognition

Self‐assembled vesicular polydiacetylene (PDA) particles with embedded metal complex receptor sites have been prepared. The particles respond to the presence of ATP and PPi (pyrophosphate) in buffered aqueous solution by visible changes of their color and emission properties. Blue PDA vesicles of uniform size of about 200 nm were obtained upon UV irradiation from mono‐ and dinuclear zinc(II)–cyclen and iminodiacetato copper [Cu^II–IDA] modified diacetylenes, embedded in amphiphilic diacetylene monomers. Addition of ATP and PPi to the PDA vesicle solution induces a color change from blue to red observable by the naked eye. The binding of ATP and PPi changes the emission intensity. Other anions such as ADP, AMP, H₂PO₄^?, CH₃COO^?, F^?, Cl^?, Br^? and I^?, failed to induce any spectral changes. The zinc(II)–cyclen nanoparticles are useful for the facile detection of PPi and ATP in millimolar concentrations in neutral aqueous solutions, while Cu^II–IDA modified vesicular PDA receptors are able to selectively discriminate between ATP and PPi.     

离子色谱-柱切换进样抑制电导检测环丁砜中的杂质阴离子

研究了采用离子色谱法-柱切换进样押制电导检测环丁砜样品中的阴离子的分析方法.采用美国Dionex公司ICS90型离子色谱仪,用9 mmol·L-1Na2CO3淋洗.一根短柱连接在定量环中作浓缩柱,进样时,首先使低浓度的环丁砜中阴离子富集在浓缩柱中,大部分对柱子可能有损害的有机物被除去,然后再切换到分析柱中进行分离检洲,可成功地测定环丁砜中的Cl-、NO3-、SO42-等痕量阴离子.实验表明该方法的检测限＜2.22×10-9,回收率为96.24%～107.51%.     

Development of a multiplex UPLC-MRM MS method for quantification of human membrane transport proteins OATP1B1, OATP1B3 and OATP2B1 in in vitro systems and tissues

OATP1B1, OATP1B3 and OATP2B1 are important members of the organic anion transporting polypeptides (OATP) family and are implicated in the hepatic disposition of endobiotics and xenobiotics. Quantitating the expression levels of human OATP1B1, OATP1B3 and OATP2B1 in in vitro systems and tissue samples could significantly improve attempts to scale up in vitro data and result in more effective in vitro–in vivo correlation of transporter-mediated effects on drug disposition, such as hepatic clearance. In the present study, a quantification method was developed, characterized, and implemented for simultaneous determination of human OATP1B1, OATP1B3 and OATP2B1 in HEK cells transfected with OATP-expressing plasmid vectors (SLCO1B1, SLCO1B3, and SLCO2B1, respectively), human hepatocytes, human brain capillary endothelial cells, and humanized mouse liver tissue using UPLC-MRM MS. Purified membrane protein standards prepared and characterized as previously reported (Protein Expr. Purif. 2008, 57, 163-71) were first used as standards for absolute quantification of the expression levels of the three human OATP membrane proteins. The specificity of the optimized MRM transitions were characterized by analyzing the tryptic digests of the membrane protein fraction of wild type HEK cells and control mouse liver tissue using the herein reported UPLC-MRM MS method. The linearity of the calibration curve spanned from 0.2 μg mL⁻¹ (0.040 μg mg⁻¹) to 20 μg mL⁻¹ (4.0 μg mg⁻¹), with accuracy (% RE) within 15% at all concentrations examined for all three OATPs of interest in this study. The intra- and inter-day assay accuracy (% RE) and coefficient of variations (% CV) of triplicates are all within 15% for all levels of quality control samples prepared by mixing the membrane fraction of control mouse liver tissue with the required amount of purified human OATP1B1, OATP1B3 and OATP2B1.     

Electrochemical Determination of Superoxide Based on Cytochrome c Immobilized on DDAB‐Modified Powder Microelectrode

Abstract

Cytochrome c was immobilized at didodecyldimethylammonium bromide (DDAB)‐modified powder microelectrode and presented quasi‐reversible electrochemistry. The apparent surface coverage of cytochrome c is greatly enhanced by using powder microelectrode technique, which is 1.21×10^?8 mol/cm², more than one to three orders of magnitude larger than that obtained with thiol and DNA‐modified Au electrode. The cytochrome c modified powder microelectrode was applied for the amperometric determination of superoxide generated by the reaction of hypoxanthine with xanthine oxidase (XOD) in the presence of dioxygen.

The detection sensitivity of the modified powder microelectrode is 0.74 µA/cm² µM, which is larger than that reported in previous publications. The detection limit of the modified powder microelectrode (PME) is 0.5 µM, and the linear detection range is 0.86～5.93 µM (values of the concentration are all in terms of hypoxanthine concentration in the solution).     

Development of One-Step Derivatization and Preconcentration Technique Using Weak Anion-Exchange Resin Modified with Sodium Diethyldithiocarbamate for Determination of Trace Amount of Copper(II) in Water

A new method was developed using weak anion exchange resin modified with sodium diethyldithiocarbamate (DDTC) for the derivatization and preconcentration of copper(II) in water prior to spectrophotometric determination. Several conditions affecting the extraction efficiency were investigated. Under the optimum conditions, an enrichment factor of 50 was achieved. The reaction mechanism of copper(II) and DDTC on the resin and binding experiment was studied. The detection limit is 0.6 μ g L^?1. The relative standard deviations of intra- and inter-day ranging from 2.1 to 3.6% and from 1.3 to 4.0% were obtained, respectively, and the recoveries were in the range of 95.3–99.6%.     

A Rapid Determination of Trace Amounts of Bismuth in Urine and Blood Using Differential Pulse Anodic Stripping Voltammetry at the Hanging Mercury Electrode

Abstract

Bismuth in 5 ml of blood or 10 ml of urine is determined by dilution to 100 ml with 0.25 M HCl, separation by anion exchange chromatography (Amberlite IRA-400 (Cl)), and measurement by differential pulse anodic stripping voltammetry in the presence of 0.1 M KCl.     

Review: Structurally characterized α-diimine complexes of s- and p-block elements

This review provides an account on the structurally characterized s- and p-block element complexes of neutral α-diimine ligands and their chemical properties. These ligands provide the opportunity to control the coordination sphere around the main group element center and electronic properties of the complexes by varying the substituents present in them. In many instances, α-diimine main group element complexes themselves undergo reactivity via redox and free radical mechanisms.