Direct electrochemistry of glucose oxidase immobilized on porous carbon nanofiber/room temperature ionic liquid/chitosan composite film and its biosensing application

The direct electron transfer of glucose oxidase (GOD) immobilized on a composite matrix based on porous carbon nanofibers (PCNFs), room-temperature ionic liquid (RTIL), and chitosan (CHIT) underlying on a glassy carbon electrode was achieved. The combination of the PCNFs, RTIL, and CHIT provided a suitable microenvironment for GOD to transfer electron directly. In deaerated buffer solutions (pH 7.0), the cyclic voltammetry of the GOD/PCNFs/RTIL/CHIT composite films showed a pair of well-defined redox peaks with the formal potential of −0.45 V (vs. SCE). The synergistic effort of the PCNFs, RTIL, and CHIT also promoted the stability of GOD in the composite film and retained its bioactivity.     

Binding of caffeic acid to human serum albumin by the retention data and frontal analysis

A new mathematical model and frontal analysis were used to characterize the binding behavior of caffeic acid to human serum albumin (HSA) based on high‐performance affinity chromatography. The experiments were carried out by injecting various mole amounts of the drug onto an immobilized HSA column. They indicated that caffeic acid has only one type of binding site to HSA on which the association constant was 2.75 × 10⁴/m . The number of the binding site involving the interaction between caffeic acid and HSA was 69 nm . The data obtained by the frontal analysis appeared to present the same results for both the association constant and the number of binding sites. This new model based on the relationship between the mole amounts of injection and capacity factors assists understanding of drug–protein interaction. The proposed model also has the advantages of ligand saving and rapid operation. Copyright © 2014 John Wiley & Sons, Ltd.     

Spectroscopic studies on the inclusion interaction of p-sulfonatocalix[6]arene with vitamin B6

The formation of the inclusion complex of p-sulfonatocalix[6]arene (SCX6) with different forms of vitamin B₆ (VB₆) was studied by using fluorescence spectroscopy. VB₆ can exist in one of three forms (the acidic form, neutral zwitterionic form and basic form) depending on pH. The fluorescence intensities of acidic and basic forms of VB₆ remarkably decreased in presence of SCX6. SCX6 preferred to form 1:1 inclusion complexes with acidic and basic forms of VB₆ but hardly form inclusion complex with neutral zwitterionic form. According to the nonlinear curve fitting method, the inclusion constant (K) for the formation of inclusion complexes of acidic and basic forms of VB₆ with SCX6 were evaluated to be 1.4?×?10⁴ and 9?×?10³ L/mol, respectively. The binding affinity of SCX6 towards acidic form is attributed to hydrogen bonds and hydrophobic interaction, furthermore, additional electrostatic interaction also plays a crucial role. The possible inclusion mode was given by ¹H NMR technique.     

Microstructural evolution during oxidative ablation in air for polyacrylonitrile based carbon fibers with different graphite degrees

Polyacrylonitrile‐based carbon fibers with different graphite degrees were oxidative ablated at 500 and 600 °C in air. By Thermal gravimetric (TG), Raman spectroscopy, X‐ray diffraction, and SEM, the mass loss, microstructure, and surface morphology of carbon fibers were investigated. The mass loss of carbon fiber increases linearly with increasing oxidative ablated time under 500 and 600 °C. The carbon fiber with higher graphite degree shows higher oxidative resistance, and the surface roughness increases gradually because of chemical ablation during the whole oxidation. A gloss morphology appears on the surface primarily because of physical denudation for carbon fibers with lower graphite degree and then burn off according to carbon and oxygen reaction. The crystallite size (La) decreases significantly, while interlayer spacing(d₀₀₂) remains nearly unchanged. SEM observation suggests the two kinds of ablation mechanisms for carbon fibers with different graphite degrees indicating that CC band in sp³ hybridization prefers to be attacked by oxygen molecule more than that in sp² hybridization during oxidation ablation in air. Copyright © 2012 John Wiley & Sons, Ltd.     

Preparative isolation of arylbutanoid‐type phenol [(‐)‐rhododendrin] with peak tailing on conventional C18 column using middle chromatogram isolated gel column coupled with reversed‐phase liquid chromatography

Reversed‐phase liquid chromatography coupled with middle chromatogram isolated gel column was employed for the efficient preparative separation of the arylbutanoid‐type phenol [(‐)‐rhododendrin] from Saxifraga tangutica. Universal C18 (XTerra C18) and XCharge C18 columns were compared for (‐)‐rhododendrin fraction analysis and preparation. Although tailing and overloading occurred on the XTerra C18 column, the positively charged reversed‐phase C18 column (XCharge C18) overcame these drawbacks, allowing for favorable separation resolution, even when loading at a on a preparative scale (3.69 mg per injection). The general separation process was as follows. First, 365.0 mg of crude (‐)‐rhododendrin was enriched from 165 g Saxifraga tangutica extract via a middle chromatogram isolated gel column. Second, separation was performed on an XTerra C18 preparative column, from which 73.8 mg of the target fraction was easily obtained. Finally, the 24.0 mg tailing peak of (‐)‐rhododendrin on XTerra C18 column was selectively purified on the XCharge C18 analytical column. These results demonstrate that the tailing nonalkaloid peaks can be effectively used for preparative isolation on XCharge C18 columns.     

磷脂囊泡的研究与应用

从脂质体的发现历史开始,对脂质体的形貌和结构等各个方面的研究成果和方法,以及脂质体的制备、物理性质、应用等进行综合性介绍。     

基于不规则衍射理论的冰晶粒子的光散射研究(英文)

在不规则衍射理论的基础上,分析了从可见光到近红外波段冰晶粒子的光散射特性。计算了粒子尺度为20μm,50μm,80μm的五种典型冰晶粒子的消光效率因子和吸收效率因子。最后,为了评估不规则衍射理论的精确性,与有限时域差分法和几何光学法进行了比较。