酯基型Gemini双季铵盐表面活性剂与DNA的相互作用

在合成系列酯基型Gemini双季铵盐表面活性剂的基础上,采用紫外可见分光光度法和荧光分光光度法考察了系列表面活性剂与DNA的相互作用。酯基型Gemini双季铵表面活性剂均未使DNA的吸收峰发生红移,即两者相互作用时没有发生嵌插作用,且与DNA相互作用的猝灭属于静态猝灭。当连接基相同时,结合常数随疏水链的增长呈先增大后减小的趋势,但当疏水链长度相同时,连接基碳链长度的变化对结合常数的影响并无明显规律。     

Gemini表面活性剂烷烃尾链在吸附和聚集过程中的疏水协同效应(英文)

以表面张力法测定了系列Gemini表面活性剂m-6-m以及对应单体表面活性剂CmTABr的临界胶束浓度(cmc)和降低水表面张力20mN·m-1需要的浓度(pC20).比较这些参数表明m-6-m胶束化和在界面吸附的能力均强于CmTABr,这被归结为Gemini表面活性剂烷烃尾链间的疏水协同效应.与不对称Gemini表面活性剂12-6-m比较,对称的Gemini结构更有利于表面活性剂的聚集和吸附.     

对磺酸基杯[4]芳烃与血红蛋白相互作用的光谱研究

用荧光光谱法和紫外可见分光光度法研究了表面活性剂存在下对磺酸基杯[4]芳烃与牛血红蛋白的相互作用机理。由Stern-Volmer方程及紫外可见吸收光谱图确定对磺酸基杯[4]芳烃对血红蛋白的荧光猝灭过程为动态猝灭,求出了猝灭常数。由热力学参数判断二者之间的作用力主要是疏水作用。依据能量转移理论得出荧光给体-受体间的距离r。在同步荧光光谱中,对磺酸基杯[4]芳烃的加入对血红蛋白构象的改变不大。     

季铵盐型阳离子表面活性剂与牛血清白蛋白的相互作用

本文合成并表征了三种不同烷基链长度的季铵盐型阳离子表面活性剂：N-十二烷基-N-（2-羟乙基）-N,N-二甲基溴化铵（DHDAB）、N-十四烷基-N-（2-羟乙基）-N,N-二甲基溴化铵（THDAB）、N-十六烷基-N-（2-羟乙基）-N,N-二甲基溴化铵（CHDAB）。采用荧光光谱法、紫外-可见光谱法、动态光散射法和等温滴定量热法对三种表面活性剂与牛血清白蛋白（BSA）的相互作用进行研究。荧光光谱研究表明,三种表面活性剂主要与BSA分子内的色氨酸残基发生相互作用,导致蛋白质的构象发生变化,且表面活性剂烷基链越长,与BSA的相互作用就越强。BSA荧光猝灭的主要原因是静态猝灭,紫外光谱实验同样验证了静态猝灭的存在。等温滴定量热法结果表明低浓度的表面活性剂与BSA主要发生静电作用和疏水作用而放热。动态光散射结果表明高浓度的表面活性剂会使BSA结构被破坏。本文揭示了表面活性剂与BSA相互作用的机理,为表面活性剂的广泛应用提供了理论基础。     

光敏季铵盐Gemini表面活性剂a4-6-m在气/液界面的吸附

合成了3种不对称结构的季铵盐Gemini表面活性剂a4-6-m, 分子的一根疏水链是偶氮苯为端基的4个亚甲基链, 另一根是不同长度的脂肪链(m=12, 14, 16). 研究结果表明, 反式偶氮苯封端的a4-6-m在气/液界面上以直立方式排列, 偶氮苯端基间的π-π相互作用导致吸附分子较为紧密地排列, 但吸附层外表面含有偶氮苯成分使临界胶束浓度(cmc)时的表面张力(γcmc)较大. 紫外光激发使反式结构偶氮苯变为顺式结构, 这些极性较强的顺式偶氮苯夹杂在直立的烷烃链间, 增强的偶极-偶极相互作用促进了分子紧密排列, 使分子占据面积(Amin)略微减小. 增长脂肪链长度有助于降低临界胶团浓度和C20(使水的表面张力降低20 mN·m-1时所需的表面活性剂浓度), 但对γcmc影响不大.     

季铵盐型Gemini表面活性剂的胶束化动力学研究

采用停流法并结合Aniannson-Wall理论, 研究了联接基为(CH2)2, (CH2)3, (CH2)4和(CH2)6的季铵盐型Gemini表面活性剂胶束的形成-破坏过程. 动力学的研究结果表明, 胶束形成-破坏过程的弛豫时间(τ2)与联接基的长度、表面活性剂的浓度、反离子的浓度以及温度有关. 随联接基长度的增加, 季铵盐型Gemini表面活性剂胶束形成-破坏过程的弛豫时间缩短. 当温度高于293 K时, 随着反离子浓度的增加, 1/τ2将出现一个最低值. 根据核化焓结果提出了不同的联接基长度的季铵盐型Gemini表面活性剂具有不同的胶束形成-破坏过程的机理.     

N-烷基-N,N-二(2-羟乙基)-N-甲基溴化铵与牛血清白蛋白的相互作用

用荧光光谱法在298K研究了Tris-HCl缓冲溶液(pH=7.1)中系列N-烷基-N,N-二(2-羟乙基)-N-甲基溴化铵(烷基链长为C12到C16)与牛血清白蛋白(BSA)的结合作用,考察了表面活性剂结构、BSA浓度对结合作用的影响,分别用Stern-Volmer方程、虚拟结合常数模型探讨了表面活性剂在浓度较低区域与BSA的作用机制.结果表明:三种季铵盐表面活性剂均对BSA内源荧光有猝灭作用,并导致其最大发射波长蓝移;表面活性剂的烷基链越长,Stern-Volmer猝灭常数和虚拟结合常数越大,表面活性剂与BSA的结合作用也越强.     

卟啉铈配合物与牛血清白蛋白的相互作用研究

利用荧光光谱法研究了卟啉铈配合物与牛血清白蛋白(BSA)的相互作用,实验结果表明:牛血清白蛋白的内源荧光能够被卟啉铈配合物有效的猝灭,并用Stern-Volmer方程确定了其荧光猝灭机理为静态猝灭,计算得到了在不同的温度和p H值条件下以及在草酸酯季铵盐(Gemini)、十六烷基三甲基溴化铵(CTAB)、十二烷基硫酸钠(SDS)三种表面活性剂胶束溶液中卟啉铈和BSA作用的结合点位数、结合常数和热力学参数,根据热力学参数表明其作用力主要为范德华力。     

酯基Gemini双季铵盐表面活性剂的研究进展

Gemini双季铵盐表面活性剂性能优异但生物和化学降解性差,在Gemini双季铵盐表面活性剂结构中引入酯基官能团可以提升产物性能。酯基Gemini双季铵盐表面活性剂含有酯基和双季铵盐基,具有高表面活性、吸附、絮凝、抗盐、湿润、乳化、杀菌防腐和易生物分解等优点,应用前景广阔。本文综述了酯基Gemini双季铵盐表面活性剂的合成路线、性能和石油化工的应用状况,结合发展需求对酯基Gemini双季铵盐表面活性剂的未来发展进行了分析和展望。     

紫外分光光度法测定海水中季铵盐的含量

提出了紫外分光光度法测定海水中季铵盐含量的方法。通过对不同浓缩倍数的海水进行紫外扫描,确定季铵盐的最大吸收波长为263nm。蒸馏水和海水中季铵盐的质量浓度和其吸光度分别在100mg·mL-1和50mg·mL-1以内呈线性关系。方法的检出限(3S/N)为3.205mg.L-1,平均回收率为94.95%,相对标准偏差(n=5)为1.9%。     

阴离子孪连表面活性剂的合成及其表/界面活性研究

合成了疏水链长度不同和连接基长度不同的7种系列阴离子孪连表面活性剂,研究了它们的表/界面活性。结果表明,它们有较低的表面张力和临界胶束浓度(CMC),有很好的表面活性。它们的CMC都在10-5~10-6mol/L之间,表面张力在26·5~34mN/m之间。它们有非常好的抗一价、二价盐的能力。除了C16-C2-C16在高于5%的NaCl溶液中会产生析出外,其余孪连表面活性剂都能耐盐20%以上。随着盐浓度的增加,孪连表面活性剂与烷烃间的界面张力逐渐降低,能达到10-3mN/m。与中原油田原油间的界面张力能降低到10-3~10-4mN/m,表明它们可应用于特高矿化度油藏提高采收率。     

β-/γ-环糊精与Gemini草酸酯季铵盐的相互作用

本文对新合成的双子草酸酯季铵盐表面活性剂以表面张力法测定了25～45℃范围内的临界胶束浓度(0.6698～0.6099mmol·L-1),并计算了胶束形成的相关热力学参数ΔGm0、ΔHm0、ΔSm0.对其与β-,γ-环糊精(β-,γ-CD)的包结作用进行了研究.β-环糊精与双子草酸酯季铵盐表面活性剂的主客体包结物包结比主要为2:1.实验结果表明,环糊精对双子草酸酯季铵盐的胶束化有显著影响.由于双子草酸酯季铵盐的水链被环糊精的空腔包裹,削弱了其胶束生成的能力,使溶液的表面张力随环糊精浓度的增加而大大增加.     

Self-assembled Gemini surfactant film-mediated dispersion stability

The force-distance curves of 12-2-12 and 12-4-12 Gemini quaternary ammonium bromide surfactants on mica and silica surfaces obtained by atomic force microscopy (AFM) were correlated with the structure of the adsorption layer. The critical micelle concentration was measured in the presence or absence of electrolyte. The electrolyte effect (the decrease of CMC) is significantly more pronounced for Gemini than for single-chain surfactants. The maximum compressive force, F(max), of the adsorbed surfactant aggregates was determined. On the mica surface in the presence of 0.1 M NaCl, the Gemini micelles and strong repulsive barrier appear at surfactant concentrations 0.02-0.05 mM, which is significantly lower than that for the single C(12)TAB (5-10 mM). This difference between single and Gemini surfactants can be explained by a stronger adsorption energy of Gemini surfactants. The low concentration of Gemini at which this surfactant forms the strong micellar layer on the solid/solution interface proves that Gemini aggregates (micelles) potentially act as dispersing agent in processes such as chemical mechanical polishing or collector in flotation. The AFM force-distance results obtained for the Gemini surfactants were used along with turbidity measurements to determine how adsorption of Gemini surfactants affects dispersion stability. It has been shown that Gemini (or two-chain) surfactants are more effective dispersing agents, and that in the presence of electrolyte, the silica dispersion stability at pH 4.0 can also be achieved at very low surfactant concentrations ( approximately 0.02 mM).     

Aggregation numbers of cationic oligomeric surfactants: a time-resolved fluorescence quenching study

The micelle aggregation numbers (N(agg)) of several series of cationic oligomeric surfactants were determined by time-resolved fluorescence quenching (TRFQ) experiments, using advantageously 9,10-dimethylanthracene as fluorophore. The study comprises six dimeric ("gemini"), three trimeric, and two tetrameric surfactants, which are quaternary ammonium chlorides, with medium length spacer groups (C(3)-C(6)) separating the individual surfactant fragments. Two standard cationic surfactants served as references. The number of hydrophobic chains making up a micellar core is relatively low for the oligomeric surfactants, the spacer length playing an important role. For the dimers, the number decreases from 32 to 21 with increasing spacer length. These numbers decrease further with increasing degree of oligomerization down to values of about 15. As for many conventional ionic surfactants, the micelles of all oligomers studied grow only slightly with the concentration, and they remain in the regime of small micelles up to concentrations of at least 3 wt %.     

Effects of Spacer Chain Length and Additives on Solution Properties of Cationic Gemini Surfactant

The critical micelle concentration (CMC) has been determined for the gemini surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium bromide)12-s-12,2Br^?1 by means of electricity conductivity measurements. For the same number of carbon atoms in the hydrophobic chain per hydrophilic head group, geminis have CMC values well below those of conventional single-chain cationic surfactants. The CMC of 12-3-12 reduces with the addition of n-alcohol except ethanol and with the increase of n-alcohol chain length as well as increase of concentration of n-butanol and sodium chloride. Steady-state fluorescence quenching technology has been employed to study the aggregation number of micelle, which increases with increase in the length of n-alcohol. The Kraft temperature measurements also indicate that the stability of solid surfactant hydrate decreases along with the improvement of concentration of n-butanol and sodium chloride.     

动态光散射法研究季铵盐Gemini表面活性剂的胶团化行为

用动态光散射技术在10～70℃温度范围内,通过测定胶团的平均流体力学半径随温度、盐浓度和联接基团长度的变化情况,研究联接基团为聚亚甲基链的阳离子季铵盐Gemini表面活性剂胶团在无机盐介质中的长大规律.实验结果表明,增加盐量、降低温度和减小联接基团的长度均使平均流体力学半径变大,Gemini表面活性剂胶团长大时是由球状转变为棒状.从实验测定的平流体力学半径求算了支配球-棒转变的平衡常数及热力学函数值,并用NNLS(non-negatively constrainedleast square)算法对胶团的粒径分布情况进行了分析.此外,对具有短联接基团的Gemini表面活性剂胶团长大所具有的独特性质进行了讨论.