基于壳聚糖膜固定双酶的胆碱传感器的研究

提出了一种基于壳聚糖膜固定辣根过氧化物酶 胆碱氧化酶的胆碱传感器的制备方法。该传感器以电聚合于玻碳电极的硫堇作为电子传递介体,在pH6. 8,外加电压-0. 2V(vs.SCE)条件下,其峰电流与浓度范围 5. 0×10-5 ~3. 0×10-3 mol/L的胆碱呈良好的线性响应;检出限为 1. 0×10-5 mol/L。传感器有良好的选择性和稳定性,使用一月后,仍能保持其初始活性的 80%。     

Spreading of dipalmitoyl phosphatidylcholine on the surface of sodium deoxycholate aqueous solution

The surface pressure vs. mokcular surface area relations for dipalmitoyl phosphatidylcholine (DPPC) insoluble monolayer and sodium deoxycholate (SDC) adsorbed monolayer,L and D1, respectively, were obtained from the analyses of surface tensions measured by the Wilhelmy glass plate. Also, D1 was obtained by a drop-weight method. Next, the surface pressure time course,(t), of the SDC aq. was measured by the Wilhelmy plate before and after DPPC was spread on the liquid surface. At DPPC spreading,(t) jumped to a maximum,, and decreased along an exponential curve. The values of with various surface amounts of DPPC and bulk concentrations of SDC were analyzed using a dual surface-region model. The model enabled the estimation of. For better fitting, modified relations were constructed in place of D1. The exponential decrease of(t) was also observed on the SDC adsorbed monolayer which was rapidly compressed by a moving barrier. The(t) relaxation rate constants of the SDC monolayers which were compressed by DPPC spreading and the moving barrier agreed with each other, suggesting a desorption of SDC from the surface.     

Solvation and Ion-Pairing Effects of Choline Acetate Electrolyte in Protic and Aprotic Solvents Studied by NMR Titrations

Choline-based electrolytes have been proposed as environmentally friendly and low-cost alternatives for secondary zinc air batteries. Choline acetate [Ch]⁺[OAc]⁻ in protic (D₂O) and aprotic (DMSO-d₆) solvents has been studied by means of concentration-dependent ¹H NMR, viscosity, and density measurements. The viscosities have been calculated on the basis of the Jones-Dole equation and showed that the dominant contribution originates from short-range ion-solvent interactions. Site-specific association affinities were assigned from NMR chemical shift titrations. In DMSO-d₆, the hydroxyl group of choline was found to have the smallest dissociation constant followed by the methyl group of acetate. The corresponding Gibbs energies at low concentration were found to be in agreement with a solvent-separated ion pair (2SIP) configuration, whereas at concentrations above 300 mM, a solvent-shared ion pair (SIP) configuration was assigned. For [Ch]⁺[OAc]⁻ in D₂O, association effects were found to be weaker, attributed to the high dielectric constant of the solvent. On time scales on the order of 100 ms, NMR linewidth perturbations indicated a change in the local rotational dynamics of the ions, attributed to short-range cation-solvent interactions and not to solvent viscosity. At 184 mM, 40 % of the cations in DMSO-d₆ and 10 % in D₂O were found to exhibit short-range interactions, as indicated by the linewidth perturbations. It was found that at about 300 mM, the ions in DMSO-d₆ exhibit a transition from free to collective translational dynamics on time scales on the order of 400 ms. In DMSO-d₆, both ions were found to be almost equally solvated, whereas in D₂O solvation of acetate was stronger, as indicated by the obtained effective hydrodynamic radii. For [Ch]⁺[OAc]⁻ in DMSO-d₆, the results suggest a solvent-shared ion association with weak H-bonding interactions for concentrations between 0.3–1 M. Overall, the extent of ion association in solvents such as DMSO is not expected to significantly limit charge transport and hinder the performance of choline-based electrolytes.     

The host-guest chemistry of resorcinarenes

Conformations, acid-base and supramolecular properties of phenolic metacyclophanes obtained from the condensation of resorcinol with aldehydes are discussed, including the mechanisms involved in the formation of these macrocycles. The strong binding of choline-type compounds and the inhibition of acetylcholine hydrolysis with therccc stereoisomers is mechanistically evaluated; arctt isomer shows strong conformational coupling for, e.g., choline binding and simultaneous proton release. The presence of larger alkyl residues at the bottom of therccc macrocycle leads to an additional binding site for small lipophilic substrates, which is independent of the upper complexation center for positively charged substrates. Substitution at the upper rim by carboxylic groups at the 2-position of the phenyl rings yields receptors for, e.g., , -diammonium ions with alternate equatorial and axial arylunits. Positively charged substituents at the upper rim, introduced by aminoalkylation, lead to little change of complexation as a result from their orientation away from the binding center. Aminoacid substituents, for the same reason, do not lead to enantioselective complexation, but allow particularly for strong binding of transition metal ions. Preliminary studies show that resorcinarenes bearing a wide array of positive charges are potent groove binders to ds-DNA without intercalative contributions.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

[Me3NC2H4OH]Zn2Cl5水溶液的激光光解研究

利用时间分辨激光光解技术研究了季铵盐型离子液体[Me₃NC₂H₄OH]Zn₂Cl₅(简写R-Zn₂Cl₅)的光解行为, 研究发现离子液体能被266 nm激光单光子电离, 生成阳离子自由基、[Zn₂Cl₅]^•中性自由基和水合电子, 观察到胆碱激发三线态的存在, 并测定了离子液体光电离的量子产额为0.04. 利用266 nm激光对离子液体、胆碱、氯化锌、氯化钠的光解行为比较, 发现胆碱阳离子的贡献很小, [Zn₂Cl₅]^－阴离子起主要作用. 采用氧化性自由基SO₄^•－引发离子自由基, 揭示其光电离机理, 测定离子液体的动力学反应速率常数, SO₄^•－ 460 nm的衰减速率常数为1.3×10⁹ L•mol^－1•s^－1, 320 nm离子自由基瞬态产物的生成速率常数为1.5×10⁹ L•mol^－1•s^－1, 两者很接近, 说明SO₄^•－自由基的衰减与瞬态自由基的生成是同步的.     

Infrared Responsive Choline Phosphate Lipids for Synergistic Cancer Therapy

Choline phosphate lipids have been designed and developed as new-generation zwitterionic nanocarriers with excellent biocompatibility and bioorthogonality to provide a more programmable performance for cancer therapy. However, there is a lack of spatiotemporal and reversible control for drug release at target tumor cells, which can lead to severe adverse effects to normal tissue and discounted treatment outcome. Here, light-inducible Lip-cRGDfk/ICG/Dox liposomes were developed for synergistic cancer therapy. ICG can effectively convert light energy into selective heating in a local environment upon laser irradiation, thus inducing thermal ablation of tumor cells, and further reversibly trigger the spatiotemporal release of anticancer drugs (Dox) at tumor cells due to the conformation transformation of CP lipids to synergistically kill tumor cells. That Lip-cRGDfk/ICG/Dox exhibited a significant improvement for breast cancer therapy in vitro and in vivo is also demonstrated, thus it can serve as an efficient platform to noninvasively and spatiotemporally control the activation of cytotoxicity at tumor cells for precision cancer therapy.     

Quaternary ammonium compounds in roots and leaves of Capparis spinosa L. from Saudi Arabia and Italy: investigation by HPLC-MS and 1H NMR

Capparis spinosa L. is a perennial plant typical of the Mediterranean flora and a multipurpose plant used for curing various human ailments. Quaternary ammonium compounds (QACs), as constituents of Capparaceae, play important roles in protecting against abiotic stress. Aim of this work was to determine QACs in root and leaves of caper from two proveniences. The presence of stachydrine, choline, glycine betaine and homo-stachydrine has been confirmed by high resolution MS, while ¹H NMR was applied to quantify the main QACs in the aqueous extracts. Stachydrine was quantified at 20.2 mg/g and 32.3 mg/g on dry leaves from South of Italy and Saudi Arabia, respectively, while a minor content was in dry roots (from 10.4 to 12.5 mg/g). Choline was considerably lower both in leaves and roots (from 0.3 to 1.2 mg/g). To our knowledge, this is the first report on the determination of QACs both in root and leaves of C. spinosa.     

Deep eutectic solvents and glycerol: a simple,environmentally benign and efficient catalyst/reaction media for synthesis of N-aryl phthalimide derivatives

Abstract

Deep eutectic solvents (DES) and glycerol have been successfully employed as efficient catalysts/reaction media in the synthesis of N-aryl phthalimide derivatives from phthalic anhydride and primary aromatic amines. The DES prepared from choline chloride and malonic acid proved to be an efficient catalyst whereas glycerol and the DES of choline chloride and urea played a dual role of catalyst and solvent. These mixtures are biodegradable, nontoxic, and cost-effective thereby providing a good industrial alternative to conventional methods. These methods gave products in moderate to high yields with good recyclability of catalyst/solvent at least up to five consecutive runs.     

Synthesis of Amphoteric Surfactants via Esterification Process

This article describes the synthesis of a novel amphoteric surfactant through esterification of 2‐hydroxy‐N,N,N‐trimethylethanaminium chloride with maleic acid alkyl ester of C₈, C₁₀, and C₁₂ chain length in the presence of base. Maleic acid alkyl esters were synthesized by the reaction of maleic anhydride with alkyl alcohol. Surface‐active properties were studied by different techniques such as surface tension and foaming property. Critical micelle concentrations (CMCs) were found by using surface tension values to learn the effect of chain length on CMC of synthesized surfactants. The best result obtained has minimal coproducts, an environmentally safer route, and a very good CMC value of surfactants.