联二炔囊泡的光致聚合、热致变色及应用

物理化学实验为各大高校本科化学教学的主干实验课程之一。虽然各高校的物理化学实验内容已十分丰富,但仍然缺乏将不同章节知识点融会贯通以及与学科前沿密切联系的综合型实验内容。我们根据南开大学郭东升教授课题组发表的一篇有关联二炔程序性响应检测胆碱酯酶的工作设计了"联二炔囊泡的光致聚合、热致变色及应用"的物理化学实验,涉及到联二炔缔合胶体的制备、联二炔的紫外光致聚合反应和聚联二炔的热致变色,进而显示其在防伪领域的潜在应用价值。希望通过此实验,使学生对物理化学中的缔合胶体、光化学、热力学、动力学等章节有更深一步的贯通性掌握,并了解自组装、光聚合、变色材料和防伪等相关研究领域的前沿动态。     

聚联乙炔囊泡负载的Bola型两亲分子识别三聚氰胺过程中Chaotrope促进型显色机制及热力学

用聚联乙炔囊泡为载体,将bola型两亲分子1,12-二乳清酸十二胺盐(DDO)对三聚氰胺的分子识别作用用肉眼可见的颜色变化显示出来.通过比较不同碳链长度的聚联乙炔囊泡对分子识别过程的反映,发现二十三烷基-2.4-二炔酸(TCDA)囊泡的显色灵敏度较高.研究表明,TCDA肉眼可见的颜色变化来自于DDO与三聚氰胺多重氢键的形成以及溶液环境中水结构的变化.为了更好地理解显色机理,用差示扫描量热(DSC)仪详细研究了分子识别过程中聚联乙炔囊泡的相变行为及热力学参数.结果表明:TCDA囊泡和带有识别分子的DDO/TCDA囊泡在三聚氰胺存在下,相变温度Tm均向高温方向移动,并且,随三聚氰胺浓度的增加,Tm值逐渐增大直至囊泡瓦解;但是Tm值的变化没有与囊泡变色必然关联,仅仅DDO/TCDA囊泡具有变色现象,而且,只有当三聚氰胺的浓度超过分子识别氢键形成所需理论量时,肉眼才能可见明显的由蓝到红的颜色变化.为了理解溶液中过量的三聚氰胺对囊泡变色的作用,选用蔗糖和尿素作为典型的水结构促进剂和水结构破坏剂(chaotrope),详细研究了它们对聚联乙炔囊泡反映分子识别过程中相变温度的影响及显色规律.结果表明,过量的三聚氰胺在溶液中起到类似尿素水结构破坏剂的作用.这种作用和分子识别过程中多重氢键的形成对聚联乙炔囊泡的变色缺一不可.本研究首次揭示了由水结构破坏剂参与的聚联乙炔囊泡变色机理,有助于理解共轭聚合物热相变过程中的Hofmeister效应.     

赖氨酸在甘草次酸弹性囊泡形成过程中的作用机制

制备和评价含赖氨酸的甘草次酸弹性囊泡, 并考察赖氨酸在囊泡形成过程中的作用机制. 在水合介质中加入赖氨酸, 利用薄膜-高压均质法制备甘草次酸弹性囊泡. 并合成了甘草次酸赖氨酸盐及其弹性囊泡作为对比制剂. 通过对粒径、zeta电位、包封率、相转变温度、变形性和体外经皮渗透性的测试, 考察赖氨酸在甘草次酸弹性囊泡中的存在形式及作用. 结果显示加入赖氨酸后, 甘草次酸弹性囊泡的粒径略有降低, 膜相转变温度降低, 包封率和囊泡变形性显著提高, 载药量提高近30倍(1.5 mg·mL-1), 并显著高于其赖氨酸盐所形成囊泡的载药量和弹性. 此外, 赖氨酸的加入使弹性囊泡的变形能力增加, 8 h累积透过量和皮肤驻留量分别提高4.3倍和9.2倍. 表明赖氨酸与甘草次酸形成离子缔合物, 促进甘草次酸参与膜的形成, 使膜的流动性增加, 赖氨酸与弹性囊泡对提高囊泡载药量起协同作用.     

单糖/双糖对近中性pH下共轭亚油酸囊泡影响的比较

比较了乳糖等3种双糖或核糖等3种单糖及其复配物对近中性范围共轭亚油酸(CLA)形成脂肪酸囊泡(FAV)的影响. 用激光丁达尔效应确定FAV的pH窗口及各相区, 用透射电子显微镜及动态光散射表征其形貌和尺寸, 用浊度法研究了其稳定性, 用等温滴定量热证明各种糖及其复配物与FAV表面的弱非共价键合作用, 并经理论计算获得结合能. 实验和计算结果表明, 各种糖及其复配物均可以双向拓宽CLA形成FAV的pH窗口, 且拓宽其近中性pH窗口的能力按照双糖<单糖≈双糖/单糖≤单糖/单糖的顺序依次增强. 主要归结为单糖在FAV表面的强竞争吸附, 以及双糖可能因多结合位点吸附而减少其自由羟基与环境水分子的缔合作用, 从而影响多羟基小分子依靠自由羟基增强囊泡表面亲水性的效果.     

利用烷基糖苷迁移和扩张共轭亚油酸囊泡pH窗口

脂肪酸囊泡(FAV)具有与脂质体类似的中空核壳结构, 且原料来源广泛, 绿色安全, 在包埋/缓释方面有重要意义. 但FAV对pH值依赖性强, pH窗口很窄并偏离生命体系适应pH范围, 限制了其作为包埋/缓释体在日用化学品及外用药等中的应用. 本文用绿色安全非离子表面活性剂烷基糖苷(APG)使共轭亚油酸(CLA)形成FAV的pH窗口从原先的8.0-9.0 迁移并扩张至6.0-8.0, 从而与生命体系适应pH值范围相匹配, 并探讨了改善FAV的pH值依赖性和敏感性的原理.     

Entrapment Efficiency of All-trans Retinoic Acid in Surfactant Vesicles

Spontaneous vesicles of dicetyl dimethyl ammonium chloride (DCDAC) and its mixture with sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) are observed respectively in ethanol-water mixed solvents, which have been demonstrated by negative-staining transmission electric microscope (TEM) and atomic force microscope (AFM). Ethanol can promote the vesicle formation, especially to pure DCDAC surfactant system. The entrapment efficiency of the vesicles to all-trans retinoic acid (ATRA) was measured by the first order derivative spectrophotometry method. The entrapment efficiency of ATRA reaches 22% in 0.5 ethanol volume ratio solution when the concentration of DCDAC is 2.5 × 10^?3 mol/L. In the same solvents, the entrapment efficiency could be as high as 62% in 1:9 (molar ratio) DCDAC/AOT mixtures when the total concentration of surfactants is 3.0 × 10^?3 mol/L.     

Inactivation of Escherichia coli on Immobilized CuO/CoFe2O4‐TiO2 Thin‐Film under Simulated Sunlight Irradiation

Composite photocatalysts of CuO/CoFe₂O₄‐TiO₂ were successfully synthesized by a sol‐gel method and fixed on ordinary tiles. The photosterilization of Escherichia coli was examined on CuO/CoFe₂O₄‐TiO₂ thin films under a xenon lamp irradiation. The film was characterized by XRD, and the morphology was observed by SEM. Disinfection data indicated that CuO/CoFe₂O₄‐TiO₂ composite photocatalysts have the much better photocatalytic activity than CuO/CoFe₂O₄ and TiO₂. The optimized composition of the nanocomposites has been found to be m_CuO/CoFe2O4:m_TiO2=3:7, with loadings ranging from 790 to 1400 mg/m². The photocatalytic inactivated rate of E. coli (10⁵ CFU/mL) reached 98.4% under the xenon lamp of 150 W within 30 min.     

Microcalorimetric Evaluation of the Effect of Kanamycin： An Analysis Based on the Median-Effect Principle

A study of the effect of drug, kanamycin, on the growth metabolism of recombinant Escherichia coli B 1 was carded out by microcalorimeter monitoring of the metabolic activity of treated cells. Power-time curves of growing recombinant Escherichia coli cell suspensions, treated with different kanamycin doses, were recorded. The extent of the effect was evaluated by changes in the slopes of the microcalorimetric curves and the kinetics of the drug action was interpreted from the time at which these changes reached their maximum values and maintained their maximum values. Experimental dose-effect relationships conform to the median-effect principle of the mass-action law： fa/（1-fa）=（D/D50）^m. A plot of y=lg[（fa）^1-1]^-1 versus x=lg D gives the slope m, D50 and R∞. The experimental results revealed that high concentration of kanamycin had an inhibitory effect on the growth of recombinant Escherichia coli B 1 in the lg phase, and had a promoting effect in the stationary period. Moreover, it was demonstrated that microcalorimetry was a reliable method for the detection of modulatory effects in biology.     

What Is the Structure of Pterodonoic Acid?

EudesmaneacidsandeudesmanelactoneshavebeendrawingattentionduetotheirwidespectrUmofbi0l0gicalpr0perties,particularlyantifeedant,cellgrowthinhibitoryandplantgr0wthregulatingactivities.l'2Inl994,Zha0andWeirep0rted'theisolationofpterodonoicacidfromLaggerapterodonta(DC)Benth,whichtheyclaimedasanewcomPoundwiththesthectureof3-oxoeudesma-4,ll-dien-l2-oicacid1.Infact,comPoundlisnotanewcomPoundandithasaPpearedinliteratureseveraltimes.hi1977,lwasfirstisolated4byBohlmannetalfromMexicangenusEuPat0riu…     

基于纳米MnO2的免标记型DNA电化学生物传感器用于大肠杆菌的测定

以室温固相合成法制备纳米MnO2,通过壳聚糖（CHIT）的成膜效应将纳米MnO2固定在玻碳电极表面。DNA在MnO2/CHIT膜上的固定和杂交通过循环伏安和电化学交流阻抗进行表征。以电化学阻抗免标记法检测目标DNA,固定于电极表面的DNA探针与目标DNA杂交后使电极表面的电子传递电阻增大,以此作为检测信号可以高灵敏度地测定目标DNA。电化学阻抗谱检测大肠杆菌基因片段的线性范围为2.0&#215;10^-11 ～2.0&#215;10^-6mol/L,检出限为1.0&#215;10^-12mol/L。     

可见光对双炔酸Langmuir膜UV聚合的影响

测量了10,12-二炔廿五碳酸单体及其聚合物的π-A曲线,Langmuir膜在10mN/m膜压10,12-二炔廿五碳酸下的紫外光聚合的分子占据面积曲线,可见光对Langmuir膜聚合的加速行为以及该聚合物的紫外可见光谱。并从聚合机理和反应中间体的电子态等角度对可见光在链增长中的作用加以讨论。     

基于纳米金／壳聚糖掺杂碳纳米管修饰金电极非标记免疫传感器的研究

应用吸附法将羊抗人IgG抗体直接固定于纳米金(GNPs)/壳聚糖(Chit)掺杂碳纳米管(CNTs)修饰的金电极表面,制备了用于人IgG抗原检测的非标记电化学免疫传感器.利用循环伏安法和交流阻抗研究了修饰电极表面的电化学特性,用差分脉冲伏安法研究了测试底液的pH值对免疫传感器性能的影响.实验表明,在含不同浓度人IgG的...