电化学方法研究环糊精与酮洛芬的包结行为

以电化学方法研究了各种环糊精及其衍生物对酮洛芬电化学行为的影响，测定了酮洛芬与β环糊精，羟丙基β－环糊精和甲基化－β－环糊精的包结常数及其温度对包结作用的影响，并由各包结物的热力学参数解释包结现象。     

β-环糊精/碳纳米管修饰电极上盐酸异丙嗪的电化学行为研究

研究盐酸异丙嗪在β-环糊精修饰多壁碳纳米管玻碳电极上的电化学行为,建立了一种新的测定盐酸异丙嗪的电化学分析方法.在碳纳米管和β-环糊精的协同作用下,用循环伏安法研究了盐酸异丙嗪在修饰电极上的氧化还原特性,结果表明该修饰电极对盐酸异丙嗪具有显著的催化氧化作用.在pH=5.4的磷酸盐缓冲溶液中,氧化峰电流与盐酸异丙嗪浓度在...     

电化学方法研究环糊精-硝基氯苯包络物

在KCl水溶液介质中，以单扫示波极谱及循环伏安法研究了硝基氯苯及其与各种环糊精包络物的电化学行为。硝基氯苯与β-环糊精、羟乙基-氨基-6去氧-β-环糊精、羟丙基-β-环糊精、羟乙基-β-环糊精的包络比均为1：1。测定了不同温度下各包络物的包络常数。通过测量溶液的热力学参数ΔH、ΔS、ΔG，讨论了包络现象。     

苯肼-α-环糊精包合物吸附行为的光谱与电化学研究

研究了水溶液体系中α环糊精(αCD)存在时盐酸苯肼(PH)的光吸收行为及电化学行为.紫外可见光谱结果表明,水溶液体系中盐酸苯肼(PH)与α环糊精(αCD)可生成1∶1包合物,经测定该包合物的包合常数(Kf)为178mol-1·dm3;与未被包合的PH相比较,PH与α环糊精生成的包合物对光及氧的敏感性质大大降低.该性质可用于改进盐酸苯肼的保存方法,并拓宽了其在医药工业中的应用范围.实验还发现水溶液体系中α环糊精存在时盐酸苯肼的电化学氧化行为得到极大的抑制.     

星形环糊精聚合物的制备及其应用

环糊精由于特殊的中空结构特点,自被发现以来一直受到研究者的关注。星形环糊精聚合物将环糊精多羟基空腔结构与星形聚合物的多臂链结构相结合,不仅具有三维空间结构,而且还具有特定的官能团以及环糊精的结构特点,具有广泛的应用前景和发展潜力。本综述主要归纳总结了以环糊精为中心的星形聚合物的制备方法,及其在生物医学、电化学、污水处理及其他方面的应用,并在此基础上对星形环糊精聚合物的发展趋势和研究方向进行了展望。     

β环糊精-碳纳米管/壳聚糖自组装膜修饰电极在过量抗坏血酸存在下测定多巴胺

基于β环糊精和碳纳米管可通过范德华力形成复合物, 利用壳聚糖分子以静电引力吸附富集碳纳米管-β环糊精, 采用层层自组装制备了β环糊精-碳纳米管/壳聚糖玻碳修饰电极, 并研究了多巴胺在修饰电极上的电化学行为. 在抗坏血酸和多巴胺共存体系中, 二者的氧化峰电位相差约163 mV, 据此建立了多巴胺的电化学选择性测定, 峰电流与浓度在1.0×10-6～7.0×10-5 mol/L 范围内呈良好的线性关系, 检出限为0.3 μmol/L.     

环糊精及其包络物的分子力学研究

本文用分子力学方法研究了环糊精及其包络物的性质, 探讨了包络过程及其驱动力, 与电化学实验结果对比获得一致性结伦。     

环糊精在电化学中的应用

本文对环糊精在电化学中的应用进行了简要的介绍。     

α-环糊精包结碳纳米管涂层电极同时测定多巴胺和肾上腺素

本文发现α-环糊精包结碳纳米管涂层电极对多巴胺（DA）和肾上腺素（EP）具有显著的增敏和电分离作用，还原峰电位差达390 mV。研究表明α-环糊精包结碳纳米管涂层薄膜表现出了非常令人感兴趣的电催化特性。因抗坏血酸（AA）在α-环糊精包结碳纳米管涂层电极上的氧化是不可逆的，因此利用还原峰进行测定，消除了AA对DA和EP的干扰。由于成本低和制作简便，该电极可用于生物系统电化学研究的生物传感器。     

离子液体功能化环糊精化合物的合成及应用

离子液体功能化环糊精化合物(ILs-CD)兼具环糊精"内疏水、外亲水"的结构特性和离子液体的低毒性、低蒸气压、电化学窗口宽、热稳定性和化学稳定性高等特性,是一类有巨大发展潜力的新型大环化合物.本文主要根据合成的ILs-CD化合物的阳离子不同对其进行了分类,并介绍了其合成方法,同时阐述了其在电化学、环境、食品、医药、催化...     

环糊精及其衍生物包合作用的理论研究进展

简要介绍了环糊精及其衍生物包合作用的理论研究进展,重点评述理论化学方法在环糊精的理化性质、环糊精包合客体分子的主要弱相互作用中的重要应用及其主要结果,并介绍了目前新的最常出现的部分理论研究方法.     

Complexation of morin with three kinds of cyclodextrin. A thermodynamic and reactivity study

Properties of inclusion complexes between morin (M) and beta-cyclodextrin (betaCD), 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) and Heptakis (2,6-O-di methyl) beta-cyclodextrin (DMbetaCD) such as aqueous solubility and the association constants of this complex have been determined. The water solubility of morin was increased by inclusion with cyclodextrins. The phase-solubility diagrams drawn from UV spectral measurements are of the A(L)-type. Also ORAC(FL) studies were done. An increase in the antioxidant reactivity is observed when morin form inclusion complex with the three cyclodextrin studied. Finally, thermodynamics studies of cyclodextrin complexes indicated that for DMbetaCD the inclusion is primarily enthalpy-driven process meanwhile betaCD and HPbetaCD are entropy-driven processes. This is corroborated by the different inclusion geometries obtained by 2D-NMR.     

Nimesulide/cyclodextrin/PEG 6000 ternary complexes: physico-chemical characterization, dissolution studies and bioavailability in rats

Purpose Ternary solid dispersions were prepared in order to estimate the effect of a double hydrophilization by cyclodextrins and PEG 6000 on nimesulide apparent characteristics. Ternary solid dispersions of nimesulide, cyclodextrins and PEG 6000 were characterized using DSC, FT-IR, dissolution studies and evaluating the bioavailability in rats. Methods Ternary solid dispersions were prepared either using native powders or using a preformed inclusion complex of nimesulide and cyclodextrin. Inclusion complexes and pure drug were used as references. Circulating nimesulide was measured out in rat plasma after orally administration of our different products (ternary solid dispersions, inclusion complexes and pure drug). Results An improvement of the nimesulide dissolution rate was obtained with inclusion complexes and ternary solid dispersion. In rat plasma, inclusion complexes and ternary solid dispersion improved T _max. Conclusions A second hydrophilization of inclusion complexes by PEG 6000 does not allow to achieve better results concerning nimesulide concentration in rat plasma or in dissolution studies than with inclusion complexes alone.     

甲基绿的电化学行为及其与环糊精形成超分子体系研究

应用“电流法”研究了甲基绿—环糊精超分子体系 ,测定了甲基绿和 4种环糊精的包结常数 .其包结能力为HP_β_CD >β_CD >SBE_β_CD >CM_β_CD ,包结比为 1 :2 (甲基绿 :环糊精 )但甲基绿与α_CD和γ_CD不能形成超分子体系 .此外 ,本文还探讨了甲基绿的电极反应机理 ,初步表明 ,甲基绿在电极上还原的电子转移数为 4 ,有 2个质子参与反应     

Complex of Porphyrins and Cyclodextrin-modified Multi-walled Carbon Nanotubes: Preparation and its Properties

A complex (C1) of tetrakis(4-hydroxylphenyl)porphyrin (THPP) and cyclodextrin-modified multi-walled carbon nanotubes (MWNTs-CD) was prepared. The UV-vis spectra show that the absorption bands of C1 are almost the same as those of THPP, implying that the electron distribution of THPP is not influenced by MWNTs-CD. On the other hand, the fluorescence of THPP is quenched, suggesting that there exists energy transfer between THPP and MWNTs-CD. In order to understand the interaction between THPP and MWNTs-CD, the electrochemical behavior of C1 was explored with cyclic voltammetry. The results display that the electrochemical behavior of C1 is similar to that of the inclusion complex of amino-modified cyclodextrin and THPP, but different from that of the MWNTs-CD. These phenomena indicate that the cyclodextrin moieties play an important role in the interaction between THPP and MWNTs-CD.     

环糊精高分子

环糊精以其独特的包合特性而引入注目，已被广泛地应用于化学分离及分析、药物控制释放、食品加工和环境保护等领域。环糊精高分子亦被证实具有包含、缓释及催化的能力，以及良好的机械强度和化学稳定性。本文综述了国内外关于环糊精高分子的类型、合成方法及实际应用的最新研究进展。     

The complexation efficiency

Studies have shown that cyclodextrins form both inclusion and non-inclusion complexes and that several different types of complexes can coexist in aqueous solutions. In addition, both cyclodextrins and cyclodextrin complexes are known to form aggregates and it is thought that these aggregates are able to solubilize drugs through micellar-type mechanism. Thus, stability constants determined from phase-solubility profiles are rarely true stability constants for of some specific drug/cyclodextrin complexes. A more precise method for evaluation of the solubilizing effects of cyclodextrins is to determine their complexation efficiency (CE). CE can be determined by measuring the solubility of a given drug at 2–3 cyclodextrin concentrations in pure water or a medium constituting the pharmaceutical formulation such as parenteral solution or aqueous eye drop formulation. Based on the CE value the drug:cyclodextrin ratio in the complexation medium can be determined as well as the increase in the formulation bulk in a solid dosage form. Determination of CE is a simple method for quick evaluating the solubilizing effects of different cyclodextrins and/or the effects of excipients on the solubilization. Here we report the CE of 43 different drugs with mainly 2-hydroxypropyl-β-cyclodextrin but also with randomly methylated β-cyclodextrin as well as few other cyclodextrins. Calculation of CE, drug:cyclodextrin molar ratio and the increase in the formulation bulk is discussed, as well as the influence of the intrinsic solubility and drug lipophilicity on the CE.     

The separation of enantiomers on modified cyclodextrin columns: Measurements and molecular modeling

The enantiomers of 2-chloropropionic acid methyl ester, cis-pinane, 2-bromoethylbenzene, 2-bromobutane, 2-hydroxybutane trifluoroacetyl ester, and styrene oxide have been resolved on an octakis-(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclo-dextrin capillary column, and the separation of the styrene oxide enantiomers has also been studied on columns coated with octakis-(3-O-trifluoroacetyl-2,6-di-O-pentyl)-cyclodextrin, octakis-(2,3,6-tri-O-pentyl)-γ-cyclodextrin, heptakis-(3-O-trifluoroacetyl-2,6-di-O-pentyl)-β -cyclodextrin, and heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin. Thermodynamic parameters (ΔG, ΔH, and ΔS) were determined from variable temperature measurements. The inclusion complexes containing styrene oxide were also studied by molecular modeling techniques. It has been found that a combined molecular mechanics–molecular dynamics approach may be a valuable tool for rationalizing the qualitative trends observed in the experimental separation factors. For the inclusion complexes considered here it is shown that the orientation of the guest relative to the cyclodextrin host is determined by the size and polarity of the cyclodextrin.     

Computational study on the molecular inclusion of andrographolide by cyclodextrin

Due to the poor water solubility of andrographolide (andro), an inclusion technique has been developed to modify its physical and chemical properties so as to improve its bioavailability. In contrast with the immense experimental studies on the inclusion complexes of andro:cyclodextrin, no computational study has so far been carried out on this system. In this work, preliminary docking experiments with AutoDock were performed. Density Functional Theory (DFT) and Austin Model 1 (AM1) calculations upon the docking instances were applied to investigate the two possible modes of molecular inclusions between andro and x-cyclodextrin (xCD, where x is alpha, beta or gamma). Atoms-in-Molecules (AIM) analysis based on the B3LYP/cc-pVDZ wavefunction was applied to verify the existence of the intermolecular hydrogen bonds. It was found that the most stable complex among the six possible inclusion complexes was the one formed between andro and betaCD with andro's decalin ring moiety wrapped by CD at a ratio of 1:1. The hydrogen bonds between andro and CD were responsible for the stability of the inclusion complexes. The calculated data were found to be consistent with the experimental results. Thus, the results of this study can aid new drug design processes.     

Study on the Inclusion Interactions of β‐Cyclodextrin and Its Derivative with Clomipramine by Spectroscopy and Its Analytic Application

Abstract

The inclusion interactions of β‐cyclodextrin (β‐CD) and its derivative, namely hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) with clomipramine (CLOM) have been investigated. The guest molecule was clomipramine and inclusion complexes were characterized by UV, ¹H NMR, ¹³C NMR, and 2D NMR spectroscopy. The main factors affecting the inclusion interaction were discussed in detail. The inclusion complexation behaviour of cyclodextrins with clomipramine was studied in an aqueous buffer solution of pH 4 and pH 5 at room temperature. According to the continuous variation method (Job's plot) applied to spectroscopy measurements a 1∶1 stoichiometry has been proposed for the complexes. Based on the significant enhancement of absorption intensity of clomipramine, a sensitive UV spectrophotometric methods with high sensitivity and selectivity were developed for determination of substance in bulk aqueous solution in the presence of β‐CD and HP‐β‐CD. The apparent association constant of the complex was 9.42 · 10³ mol^?1 L and 9.58 · 10³ mol^?1 L and the linear range was 17.6–70 µg mL^?1 with a correlation coefficient of 0.9997 and a relative standard deviation (R.S.D.) of 0.97% and 1.02% using β‐CD and HP‐β‐CD, respectively. There was no interference from the excipients normally used in tablets and capsules. The proposed methods were successfully applied to the analysis of clomipramine in pharmaceuticals with satisfactory results.