某些有机物在氧化物载体表面的自发单层分散

自发单层分散原理已在载负型催化剂制备、再生等方面得到越来越广泛的应用[1，2]．许多氧化物和盐类可以在载体表面形成单层分散或亚单层分散．有些分散物与载体混合后在低于其熔点的温度下处理，就可以自发分散到载体表面[1，3]．这一现象通过XRD、LRS、XPS、SIMS、ISS、EXAFS     

有机物化学检验法的分析、讨论与应用

随着仪器分析的发展和广泛应用,针对有机化合物的化学鉴别方法研究近年来逐渐淡出化学学科前沿。然而化学鉴别方法由于其广泛的实用性和较低的成本,仍在有机定性与定量分析中占有一席之地。从典型有机物的化学鉴定分析方法入手,根据机理分类阐述了各类有机物的化学检验,并详细地讨论了几种机理较为复杂或易存在认识误区的化学检验手段,如茚三酮定性定量测试、双缩脲定性定量测试、Fehling与Benedict定性测试等。     

细胞膜上信号转导蛋白的单分子成像与分析

结合本课题组的研究工作,介绍了单分子荧光成像原理、荧光标记方法及数据分析方法,并进一步综述了单分子荧光成像在几种重要的膜蛋白信号转导分子机制和相关药物研究中的进展.     

三维荧光光谱研究垃圾渗滤液水溶性有机物与汞相互作用

为了研究垃圾填埋过程中渗滤液水溶性有机物(DOM)对重金属配位能力的影响,采用三维荧光光谱、共振瑞利散射、荧光猝灭滴定技术及非线性回归拟合分析,研究了不同填埋年限渗滤液DOM与Hg(II)的相互作用过程.结果表明: Hg(II)与DOM中不同荧光基团配位比接近1: 1,配位过程中没有生成沉淀;不同填埋年限渗滤液DOM中类蛋白物质和类富里酸物质与Hg(II)配位的条件稳定常数分别为4.30～5.70和4.35～4.98;参与配位的荧光基团分别为54.1%～92.3%和35.8%～60.1%.随着填埋年限的增加,类富里酸物质对Hg(II)的配位能力降低,但参与配位的荧光基团的比例增加.渗滤液DOM-Hg(II)配位过程受介质pH值的影响,在酸性和碱性范围内尤为明显.     

结合新药研发探讨有机物的水溶性问题

有机物的溶解度在新药研发、医药农工的检验分析等领域具有重要的应用价值,但现有本科化学教材对相关内容阐述不够准确、深入,导致学生知识储备不足。针对该现状,结合新药设计等应用领域厘清溶解度相关概念之间的联系,阐明溶解过程涉及的机理,讨论从分子结构层面提高有机物水溶性的策略。指出水溶性可通过脂水分配系数与熔点等系数求算;并且水溶性与脂溶性可同时升高;氢键的增加或消除均可能提高水溶性;分子平面性的破坏是提高分子水溶性的新策略。由此促进理论教学联系实际情况,加深师生对相关知识的理解。     

超高交联吸附树脂对芳香有机物的吸附机理

通过3种吸附树脂AmberliteXAD-4、AM-1和JX101对芳香化合物苯胺、苯酚和苯甲酸在不同温度下的吸附特征,利用前线轨道理论进行了合理解释。结果表明,吸附剂表面进行适当的修饰,可以改变吸附剂的LUMO或HOMO,使吸附质分子与吸附剂表面的功能基产生化学作用,从而产生额外的化学吸附量,为优化设计吸附剂提供了理论指导。     

由单层薄水铝石制备的活性氧化铝处理水中氟离子

The preparation of high-efficiency and low-cost adsorbents for the defluoridation of drinking water remains a huge challenge. In this study, single-layer and multi-layer boehmite were first synthesized via an organic-free method, and active alumina used for fluoride removal from water was obtained from the boehmite. The advantage of a single layer is that more aluminum is exposed to the surface, which can provide more adsorption sites for fluoride. The active alumina adsorbent derived from single-layer boehmite exhibits a high specific surface area and excellent adsorption capacity. The high surface area ensures a high adsorption capacity, and the organic-free synthesis method lowers the preparation cost. The as-prepared adsorbent was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption analysis. The single-layer structure of boehmite was determined from the simulated XRD diffraction pattern of single-layer boehmite. The disappearance of the (020) diffraction peak of boehmite illustrates that the dimensions in the b direction are extremely small, and according to the XRD simulation results, the single-layer structure of boehmite could be determined. Single-layer boehmite with a surface area of 789.4 m²·g^-1 was formed first. The active alumina obtained from the boehmite had a surface area of 678.4 m²·g^-1, and the pore volume was 3.20 cm³·g^-1. The fluoride adsorption of the active alumina was systematically studied as a function of the adsorbent dosage, contact time, concentration, co-existing anions, and pH. The fluoride adsorption capacity of the active alumina obtained from the single-layer boehmite reached up to 67.6 mg·g^-1, which is higher than those of most alumina adsorbents reported in the literature. The adsorption capacities of the active alumina are related to the specific surface area and the number of hydroxyl groups on the surface. Dosages of 0.6, 1.0, and 2.6 g·L^-1 of active alumina were able to lower the 10, 20, and 50 mg·L^-1 fluoride solutions, respectively, below the maximum permissible limit of fluoride in drinking water in China (1.0 mg·L^-1), suggesting that the active alumina synthesized in this work is a promising adsorbent for defluoridation of drinking water. In addition, the fluoride adsorption is applicable in a wide pH range from 4 to 9 and is mainly interfered by SO₄^2- and PO₄^3-. Further investigation suggested that the fluoride adsorption of the active alumina follows the pseudo second-order model and Langmuir isotherm model     

单酮类有机物气相色谱保留值与结构参数的相关性

应用半经验量子化学AM1方法和分子图形学技术获得了42种单酮类有机物分子的电子结构和几何结构参数，并将这些参数与它们在非极性固定相(SE-30柱)上的气相色谱保留值相关联，采用逐步回归分析方法，成功地建立了拟合度高、物理意义明确、预测能力强的气相色谱保留值一结构参数定量关系方程，找出了影响气相色谱保留值的主要结构因素．     

堆肥过程不同分子量水溶性有机物电子转移能力的演变及影响因素

利用超滤技术、电化学方法和光谱技术, 以堆肥水溶性有机物的不同分子量(MW)组分为研究对象, 分析在堆肥过程中不同分子量水溶性有机物(DOM)的组成特征、结构演变和电子转移能力变化的影响因素.结果表明, 类蛋白物质主要存在于堆肥前期的DOM(MW<1 kDa)中, 随着堆肥的进行, 类蛋白物质不断降解, 类富里酸物质持续合成, 堆肥后期类蛋白物质被完全降解, 类富里酸物质成为DOM(MW<1 kDa)主要的荧光组分.类腐殖物质是DOM(MW=1～3 kDa)、DOM(MW=3～5 kDa)和DOM(MW>5 kDa)的主要荧光组分, 堆肥过程中类腐殖质物质在3种不同分子量组分的变化各不相同, 但是堆肥后期类腐殖质物质在3个不同分子量组分的含量均高于堆肥初期. 堆肥过程中DOM(MW<1 kDa)的电子供给能力(EDC)呈降低趋势, 而电子接受能力(EAC)呈升高趋势; DOM(MW>5 kDa)的EDC在堆肥过程中呈上升趋势, 而EAC则无明显的变化规律.DOM(MW=1～3 kDa)和DOM(MW=3～5 kDa)的EDC和EAC在整个堆肥过程无明显变化规律.不同分子量组分堆肥DOM 的EAC受控于堆肥过程木质素降解产物的含量, 而其EDC变化与荧光参数和紫外参数无明显关系.     

平板双分子层脂膜的制备及锌离子跨该膜的输运过程

制备了氧化胆固醇 卵磷脂(脑磷脂)平板双分子层脂膜,研究了膜配方对双分子层脂膜的稳定性和离子通透性的影响,得到了最佳制膜工艺,建立了锌离子跨卵 (脑 )磷脂膜的吸附 -扩散模型,其计算值与实验值基本吻合.     

季铵盐型金属卟啉的合成及其对大肠杆菌生长代谢的抑制作用

以5,10,15,20-四(4′-吡啶基)卟啉为原料,合成了一系列季铵盐型金属卟啉1a,1b和2a～2c.使用LKB2277热活性监测器测定了大肠杆菌在不同浓度的金属卟啉1a,1b和2a～2c作用下的产热曲线,得到了大肠杆菌生长速率常数k,最大发热功率P_max和最大发热功率的出现时间t_p,发现季铵盐型金属卟啉2c对大肠杆菌生长代谢的抑制活性明显大于其它季铵盐型金属卟啉.     

Membrane Extraction of Volatile Organic Compounds in Combination with Mobile Gas Chromatographic Analysis

Abstract

The field of application of a mobile gas chromatographic device (Airmobtx monitor HC 1000 manufactured by Airmotec GmbH) originally conceived for the analysis of BTEX in air was extended to water analysis by using it in conjunction with membrane extraction. Volatile organic compounds diffuse out of water through a hollow fibre or flat membrane, are enriched onto sorption tubes integrated in the device, and then thermally desorbed and analysed by the gas chromatograph/flame ionisation detector. The suitability of various flat membranes and hollow fibres was investigated. Maximum extraction efficiency was obtained with a silicone hollow fibre measuring 0.3 m long, and with an inner diameter of 0.7 mm and a wall thickness of 100 μm. The extraction parameters were optimised. The linear dynamic range of the optimised method spans two orders of magnitude and the detection limits were found to be 0.1 μg/L for all BTEX compounds. By way of environmental applications, highly contaminated groundwater samples were analysed. The results correspond well to those achieved using conventional headspace/gas chromatography/flame ionisation detection.     

Binding Characteristics Study of DNA based Aptamers for E. coli O157:H7

E. coli O157:H7 is a pathogenic bacterium producing verotoxins that could lead to serious complications such as hemolytic uremia syndrome. Fast detection of such pathogens is important. For rapid detection, aptamers are quickly gaining traction as alternative biorecognition molecules besides conventional antibodies. Several DNA aptamers have been selected for E. coli O157:H7. Nonetheless, there has not been a comparative study of the binding characteristics of these aptamers. In this work, we present a comprehensive analysis of binding characteristics including binding affinity (K_d) and binding capacity (B_max) of DNA-based aptamers for E. coli O157:H7 using qPCR. Our results show that aptamer E18R has the highest binding capacity to E. coli 157:H7 and the highest specificity over non-pathogenic E. coli strains K12 and DH5α. Our study also finds that the common biotin-tag modification at 5′ end typically changes the binding capacity significantly. For most of the selected aptamers, the binding capacity after a biotin-tag modification decreases. There exists a discrepancy in the binding capability between the selected aptamer and the aptamer used for detection. Our study also shows that a lower concentration of Mg²⁺ ions in the binding buffer leads to a decrease in the binding capacity of E17F and E18R, while it does not affect the binding capacity of S1 and EcoR1.     

基于DNA-甲苯胺蓝生物聚合离子膜的多环有机物电化学传感器的研究

利用DNA与小分子之间的相互作用,以DNA/壳聚糖生物聚合离子膜固定电活性小分子,制备了DNA-甲苯胺蓝/壳聚糖聚合离子复合膜修饰电极,并利用多环有机物与染料分子对DNA特异结合的竞争关系,构筑了多环有机物非试剂添加型DNA电化学生物传感器。以盐酸四环素为模式分子,利用循环伏安法和方波伏安法研究了该修饰电极的电化学特性以及该电极对盐酸四环素的电化学响应,结果表明,DNA和甲苯胺蓝成功地固定在电极表面,电极表面的甲苯胺蓝保持了很好的电化学活性。利用紫外-可见分光光度法研究了电极对盐酸四环素响应的作用机理。该传感器的线性范围为2.5~100μmol·L-1。     

An Unconventional Polymerization Route to Hydrophilic Fluorescent Organic Nanoparticles for Multicolor Cellular Bioimaging

We demonstrated an unconventional polymerization route to synthesize hydrophilic fluorescent organic nanoparticles (FONs) for multicolor cellular bioimaging in this contribution. The route benefits from our unexpected discovery of a rapid polymerization reaction between 1,6‐hexanediol dipropiolate and 2,4,6‐triazide‐1,3,5‐triazine under the catalysis of N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA). Interestingly, the 2,4,6‐triazide‐1,3,5‐triazine and PMDETA system can also induce rapid free radical polymerization at room temperature. The as‐prepared FONs exhibited promising water solubility and stability with an average diameter of 20 nm. The excitation wavelength‐dependent fluorescent properties endow the FONs with blue, yellow, and red fluorescent emission under UV, blue, and green excitation, respectively. The cytotoxicity of FONs was investigated by using a Cell Counting Kit (CCK‐8) assay, which indicated good biocompatiblity. More importantly, the cell uptake experiment verified the FONs were excellent fluorescent nanoprobes for multicolor cellular bioimaging. Therefore, this unconventional route provides a novel fabrication strategy of highly hydrophilic FONs for biomedical applications.     

Regulation of Scaffold Cell Adhesion Using Artificial Membrane Binding Proteins

The rapid pace of development in biotechnology has placed great importance on controlling cell–material interactions. In practice, this involves attempting to decouple the contributions from adhesion molecules, cell membrane receptors, and scaffold surface chemistry and morphology, which is extremely challenging. Accordingly, a strategy is presented in which different chemical, biochemical, and morphological properties of 3D biomaterials are systematically varied to produce novel scaffolds with tuneable cell affinities. Specifically, cationized and surfactant‐conjugated proteins, recently shown to have non‐native membrane affinity, are covalently attached to 3D scaffolds of collagen or carboxymethyl‐dextran, yielding surface‐functionalized 3D architectures with predictable cell immobilization profiles. The artificial membrane‐binding proteins enhance cellular adhesion of human mesenchymal stem cells (hMSCs) via electrostatic and hydrophobic binding mechanisms. Furthermore, functionalizing the 3D scaffolds with cationized or surfactant‐conjugated myoglobin prevents a slowdown in proliferation of seeded hMSCs cultured for seven days under hypoxic conditions.

     

Investigation of the Effect of Four Organic Acids in Radix Isatidis on E. coli Growth by Microcalorimetry

The inhibitory effects of four organic acids (OAs) in Radix Isatidis, a traditional Chinese medicinal herb, on Escherichia coli (E. coli) growth were investigated by microcalorimetry. The power‐time curves of E. coli growth with and without OAs were acquired, meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by growth rate constants (k₁, k₂), half inhibitory ratio (IC₅₀), maximum heat output (P_max) and peak time (t_p). The values of k₁ and k₂ of E. coli growth in the presence of the four OAs decreased with the increasing concentrations of OAs. Moreover, P_max was reduced and the value of t_p increased with increasing concentrations of the four drugs. The sequence of anti‐microbial activity of the four OAs was: syringic acid>2‐amino‐benzoic acid>salicylic acid>benzoic acid. IC₅₀ of the four OAs was respectively 56 µg/mL for syringic acid, 75 µg/mL for 2‐amino‐benzoic acid, 86 µg/mL for salicylic acid and 224 µg/mL for benzoic acid. The existence of the functional groups on phenyl ring improves the anti‐microbial activity compared to benzoic acid. The functional groups methoxyl at C(3) and C(5) improve anti‐microbial activity more strongly than the other functional groups, and the functional group amino at C(2) improve anti‐microbial activity more strongly than hydroxyl at C(2) on phenyl ring.     

高效液相色谱法测定大鼠肝过氧化物酶体膜磷脂

 用 HPL C测定了过氧化物酶体膜磷脂的含量。用 Folch法提取膜脂质 ,以 μ-Porasil Si60为固定相 ,以乙腈-甲醇 -磷酸为流动相 ,采用梯度洗脱 ,紫外检测波长 2 0 5 nm。标准回收率 :心磷脂 (C)为 (1 0 3 .97± 1 2 .5 7) % ,磷脂酰肌醇 (PI)为 (88.2 3± 5 .42 ) % ,磷脂酰丝氨酸 (PS)为 (90 .3 3± 6.84) % ,磷脂酰乙醇胺 (PE)为 (84.41±1 0 .2 2 ) % ,磷脂酰胆碱 (PC)为 (89.78± 8.70 ) % ,鞘磷脂 (SM)为 (84.0 4± 1 2 .0 6) %。最小检出限分别为 :C1 2ng,PI 8ng,PS 2 3 ng,PE 4ng,PC 2 3 ng,SM 7ng。线性关系与回收率较好 ,结果令人满意。     

Binding of Organic Pollutants to Soil Organic Matter

Abstract

Binding of organic pollutants to water-soluble, low-molecular weight humic substances increases their mobility in soil and their leaching, whereas binding to high-molecular weight humic substances results in unextractable residues. Water-soluble pollutants in leachate may be bound to low-molecular weight humic material, or may be free water-soluble conversion products that are slowly released from a soil-bound form, as shown for a conversion product of the insecticide aldrin. Unextractable soil-bound 4-chloroaniline was isolated by supercritical methanol extraction 16 years after application of the phenylurea herbicide buturon to soil. Biodegradation and bioavailability of unextractable soil-bound residues are greatly reduced as compared to the free compounds. For some chlorinated anilines and phenols, biomineralization and plant uptake was shown to be highest for residues bound in fulvic acids and lowest for those in humic acids. Model experiments demonstrate that chlorinated anilines form covalent bonds with humic acid precursors.     

Single‐Molecule Methods to Study Membrane Receptor Oligomerization

Membrane receptors control fundamental cellular processes. Binding of a specific ligand to a receptor initiates communication through the membrane and activation of signaling cascades. This activation process often leads to a spatial rearrangement of receptors in the membrane at the molecular level. Single‐molecule techniques contributed significantly to the understanding of receptor organization and rearrangement in membranes. Here, we review four prominent single‐molecule techniques that have been applied to membrane receptors, namely, stepwise photobleaching, Förster resonance energy transfer, sub‐diffraction localization microscopy and co‐tracking. We discuss the requirements, benefits and limitations of each technique, discuss target labeling, present a selection of applications and results and compare the different methodologies.