Characterization of antithrombin III from human plasma by two-dimensional gel electrophoresis and capillary electrophoretic methods

The isoforms distribution of the glycoprotein antithrombin III (ATIII) derived from human plasma was investigated by means of isoelectric focusing (IEF) in polyacrylamide gels with immobilized pH gradients (IPG) and two-dimensional gel electrophoresis (2-DE) as well as capillary electrophoretic methods. It turned out that the presence of high concentrations of chaotropics (urea, thiourea) and zwitterionic detergents (3-[(3-cholamidepropyl)dimethylammonio]-1-propanesulfonate (CHAPS)) was decisive for attaining good resolution of the protein isoforms. Resolution by IPG-IEF was obtained with excellent reproducibility and pI differences down to 0.01 pH units could be distinguished. ATIII-alpha and ATIII-beta-fractions preseparated by heparin affinity chromatography showed an analogous but shifted spot pattern consisting each of one major and three minor isoforms. The main isoforms of ATIII-alpha and ATIII-beta exhibit pI values of 5.18 and 5.32, respectively, both values determined in the presence of high concentrations of urea. The pI difference of 0.14 pH units correspond to the effect of two sialic acids absent in ATIII-beta. The formation and occurrence of ATIII dimers and trimers turned out to be dependent on the sample preparation. The results obtained by 2-DE were compared with those of capillary zone electrophoresis (CZE) and capillary IEF (CIEF). Quantitative analysis regarding the CZE separated isoforms of plasma derived ATIII yielded a content of about 70% ATIII-alpha main isoform and about 6.6% of ATIII-beta. The pI values of ATIII determined by CIEF with internal calibration were in fair agreement with the pI values of the main isoforms achieved with 2-DE.     

Speciation analysis of platinum antitumoral drugs in impacted tissues

Chemical compounds containing platinum have been employed since 1978 as drugs to beat certain type of tumours. Nevertheless, besides of their exceptional antitumoral properties, these drugs also have important deleterious side effects, such as, nephrotoxicity and ototoxicity.A study of Pt accumulation and a speciation analysis has been performed by ICP-MS in samples from kidney and inner ear in a controlled population of Wistar rats treated with, either, cisplatin, carboplatin or oxaliplatin. The results on Pt accumulation point out to drug structure and not only to Pt content as the responsible for the alteration of organ functionality.Speciation studies in the samples from kidney and inner ear were performed coupling two-dimensional liquid chromatography (2D-LC) to ICP-MS. Size exclusion (SEC) and anion exchange fast protein liquid chromatography (FPLC) was employed for 2D orthogonal separation. After these separations, free drug peaks were not observed in any of the samples.The binding of Pt to biomolecules was demonstrated by SEC and, independently of the drug used, Pt eluted as two main bands with molecular weights of 12 kDa and 25-65 kDa for inner ear samples, and as two different bands with 20 kDa and 50-60 kDa in the samples from kidney. However, the relative band intensity presented important differences for the three drugs. Using the same chromatographic conditions, it was shown that a metallothionein (MT) standard eluted in the same position as some of the cytosolic Pt-biomolecules.High Pt-containing fractions eluting from the SEC column were analysed by anion exchange FPLC after a preconcentration step. Among the different preconcentration methods tested, sample focusing on the head of the FPLC column shows main advantages. In this way, the separation by 2D chromatography of the high molecular Pt-species has been considerably improved.     

多色蓝在核酸分子上的Langmuir聚集吸附

用微相吸附-光谱修正（MPASC）新技术研究核酸与多色蓝(PCB)探针分子间的相互作用，分析核酸分子内双静电膜的形成与Langmuir吸附的关联性.通过pH 7.24的介质核酸-PCB反应的光谱研究，测定了结合产物的物理化学参数：结合比1PCB:2DNA-PCB、1PCB:3RNA-PCB, 平衡常数KDNA-PCB=5.42×104， KRNA-PCB=2.82×104,摩尔吸收系数ε(DNA-PCB, 625 nm)=5.65×103（mo1－1•L ）•cm－1， ε(RNA-PCB, 625 nm)=3.85×103 （mol－1•L）•cm－1.结果表明， RNA分子仅形成约60％双螺旋结构链，核酸双螺旋每一周期的负静电沟最大聚集10个PCB分子.该吸附反应用于核酸样品测定，结果良好.     

Tuning the Hybridization of Local Exciton and Charge-Transfer States in Highly Efficient Organic Photovoltaic Cells

Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non-radiative energy loss ( ) is the dominant factor that hinders further improvements in state-of-the-art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed . Herein, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge-transfer (CT) state ratio in its hybridization with the local exciton state to facilitate charge generation, but simultaneously result in a larger . These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.     

四氮大环-金属配合物与DNA作用的电化学及谱学研究

Mononuclear copper（Ⅱ）, nickel（Ⅱ） and cobalt（Ⅲ） tetracoordinate macrocyclic complexes were synthesized and spectroscopically characterized. The crystal structure of the three compounds were determined by X-ray crystallography. The electrochemical experimental results indicate that the three complexes could interact with DNA mainly by electrostatic interaction. The interaction of tetracoordinate macrocyclic cobalt（Ⅲ） complex with DNA was studied by cyclic voltammetry and UV-vis spectroscopy. The experimental results reveal that tetracoordinate macrocyc- lic cobalt（Ⅲ） complex could interact with DNA by electrostatic interaction to form a 1 ： 1 DNA association complex with a binding constant of 7.50 ×10^3 L·mol^-1.     

Model of the Negative DC Corona Plasma: Comparison to the Positive DC Corona Plasma

A numerical model of the negative DC corona plasma along a thin wire in dry air is presented. The electron number density and electric field are determined from solution of the one-dimensional coupled continuity equations of charge carriers and Maxwell's equation. The electron kinetic energy distribution is determined from the spatially homogeneous Boltzmann equation. A parametric study is conducted to examine the effects of linear current density (0.1–100 A per cm of wire length), wire radius (10–1000 m), and air temperature (293–800 K) on the distribution of electrons and the Townsend second ionization coefficient. The results are compared to those previously determined for the positive corona discharge. In the negative corona, energetic electrons are present beyond the ionization boundary and the number of electrons is an order of magnitude greater than in the positive corona. The number of electrons increases with increasing gas temperature. The electron energy distribution does not depend on discharge polarity.     

基于三维静电势参数研究C60溶解性的构效关系

在量子化学从头算基础上,对一系列溶剂化合物分子进行了结构优化和三维静电势参数计算,运用多元线性回归分析和神经网络方法对C60在121种不同溶剂的溶解性与计算的结构参数进行了构效关系研究.用建立起来的QSPR 关系式对15种不同结构类型溶剂进行了预测,并阐述了C60溶质与不同溶剂之间的相互作用,获得了满意的结果.     

The transitional isoelectric focusing process

The transitional isoelectric focusing (IEF) process (the course of pH gradient formation by carrier ampholytes (CAs) and the correlation of the focusing time with CA concentration) were investigated using a whole-column detection capillary isoelectric focusing (CIEF) system. The transitional double-peak phenomenon in IEF was explained as a result of migration of protons from the anodic end and hydroxyl ions from the cathodic end into the separation channel and the higher electric field at both acidic and basic sides of the separation channel. It was observed that focusing times increase logarithmically with CA concentration under a constant applied voltage. The correlation of focusing time with CA concentration was explained by the dependence of the charge-transfer rate on the amount of charged CAs within the separation channel during focusing.     

POLYCATION EFFECTS ON ELECTRONIC SPECTRA OF CONJUGATED POLYMERS IN PROGRAMMED ELECTROSTATIC ASSEMBLIES

A polysaccaride, chitosan, has been used to study polycation effects on electronic spectra of conjugated polymers in programmed electrostatic assemblies. Conjugated polyelectrolytes, poly[2-(3-thienyl)-ethanolhydroxycarbonylmethylurethane] (HPURET) and polydiacetylene from 5,7-dodecadiyn-1,12-bis-(hydroxycarbonylmethylurethane) (HP4BCMU), were assembled from aqueous solution alternately with the polycation, poly (diallydimethylammonium) chloride [PDADMAC], and with the polysaccharide cation, chitosan. Switching polycations did not significantly change the visible absorption spectra for HP4BCMU multilayers. The optical properties of the regiorandom polythiophene, HPURET, depend distinctly on the polycation and the pH of the solution, showing significant differences on visible absorption maxima of the assemblies ranging from 435 nm to 516 nm. After the assemblies were exposed to vapor of aqueous ammonia, they showed UV-vis maxima further red shifted and an enhanced emission intensity, compared to those of the original assemblies. A chitosan/HPURET complex was prepared as a precipitate from solution. Its visible absorption maximum is at 536 nm with a shoulder at 580 nm, reminiscent of regioregular poly(3-alkylthiophenes). This unusual sensitivity of conjugated polymers to polycations may have potential application in sensor devices.