【作者】 邰书信；

【导师】 高志农；

【作者基本信息】 武汉大学 ， 高分子化学与物理， 2012， 博士

【摘要】 Gemini表面活性剂是一类新型的表面活性剂,可看做是传统的单亲水头基单疏水尾链表面活性剂的二聚体或寡聚体。与传统的表面活性剂相比,Gemini表面活性剂具有更高的表面活性以及更丰富的自组织行为,其分子结构也具有更大的可调控性。Gemini表面活性剂的优良性质使得它在近二十年来成为胶体界面领域内的研究热点。阴离子表面活性剂,尤其是烷基苯磺酸盐和烷基硫酸盐类表面活性剂,在工农业生产以及科研领域有着极为广泛的应用。设计和合成新型的烷基苯磺酸盐和烷基硫酸盐类阴离子Gemini表面活性剂,研究其结构与性能的关系,已成为表面活性剂科学一个重要的方向。在实际应用时,表面活性剂经常要和高分子一起使用。蛋白质是一类重要的生物大分子,蛋白质-表面活性剂复配体系在洗涤剂、化妆品、生物、医药和食品等诸多领域有着广泛的应用。因此,研究表面活性剂和蛋白质的相互作用具有重要的理论意义和实用价值。本文合成了一类烷基苯磺酸盐以及一类烷基硫酸盐类的阴离子表面活性剂,并研究了它们的表面活性以及与牛血清蛋白(BSA)的相互作用。论文主要研究内容和结果如下：1.对Gemini表面活性剂,尤其是阴离子型Gemini表面活性剂的合成、性质以及与BSA的相互作用进行了系统的文献综述。2.以长链烷基羧酸、苯胺以及1,6-己二异氰酸酯等为原料合成了四种疏水尾链长度不同的烷基苯磺酸盐Gemini表面活性剂,产物的结构用红外(FT-IR)核磁共振氢谱(1H NMR)和电喷雾电离质谱(ESI-MS)进行了表征。3.以溴癸烷、丙二酸二乙酯以及二溴代烷烃等为原料合成了四种连接基团长度不同的烷基硫酸盐Gemini表面活性剂,产物的结构用FT-IR、1H NMR和ESI-MS进行了表征。4.用表面张力法、电导法以及稳态荧光法研究了烷基苯磺酸盐Gemini表面活性剂的表面活性和胶束化性质。此类Gemini表面活性剂的临界胶束浓度(cmc)比相应的单链表面活性剂低1～2个数量级,随着疏水尾链长度的增加,四种Gemini表面活性剂的cmc先减小后增大,摩尔电导率实验证实了GeminiⅣ溶液中存在预胶束。芘荧光探针实验表明,烷基苯磺酸盐Gemini表面活性剂胶束的微极性随疏水尾链长度的增加变化不大。此类表面活性剂的发泡性和泡沫稳定性以及润湿性较差,但具有优良的钙皂分散性,其乳化力也优于十二烷基苯磺酸钠。5.用表面张力法、电导法以及稳态荧光法研究了烷基硫酸盐Gemini表面活性剂的表面活性和胶束化性质。由电导法测得的cmc比表面张力法测得的cmc要高很多,而和荧光探针法估算得到的cmc比较接近。摩尔电导实验揭示了此类表面活性剂溶液中存在预胶团现象。预胶团的存在是导致不同方法测得的cmc产生差异的原因,在这种情况下,传统的cmc是指由电导法测得的结果。四种表面活性剂的cmc随着连接基团疏水碳原子数的增加有下降的趋势。四种Gemini的发泡性和润湿性比十二烷基硫酸钠(SDS)差,且发泡性随着连接基团疏水碳原子数的增加而降低,但是泡沫稳定性比SDS要高很多,乳化力和钙皂分散性都优于SDS。6.采用荧光光谱法、紫外光谱法和圆二色谱法研究了烷基苯磺酸盐Gemini表面活性剂与BSA的相互作用。芘荧光探针实验表明,四种Gemini表面活性剂与BSA形成的复合物的微极性相差不大,而且在高浓度时与不加BSA的表面活性剂自由胶束的微极性相近。同步荧光结果证实,Gemini主要和BSA上的色氨酸残基发生相互作用。BSA内源荧光光谱变化表明,Gemini的加入导致BSA荧光的猝灭,猝灭过程同时包含了静态猝灭和动态猝灭。在低浓度时,四种Gemini使BSA荧光猝灭的速率随疏水尾链长度先增强后减弱,这是由两种相反的因素造成的：疏水尾链短的Gemini更容易接近BSA的疏水空穴与其中的色氨酸残基作用,而疏水尾链长的Gemini更容易和BSA发生疏水相互作用。圆二色谱结果表明,表面活性剂加入后导致BSA的二级结构发生变化,a-螺旋含量降低,p-折叠含量增加。7.采用荧光光谱法、圆二色谱法以及动态光散射法研究了烷基硫酸盐Gemini表面活性剂与BSA的相互作用。芘荧光探针实验表明,Gemini表面活性剂与BSA形成的复合物的微极性随着连接基团疏水链长的增加而降低,并且比相应的表面活性剂自由胶束的微极性要低。BSA内源荧光和同步荧光分析结果表明,BSA在变性过程经历了一个中间态,中间态相对于BSA以及部分变性的BSA具有更强的形成聚集体的倾向。圆二色谱实验表明,烷基硫酸盐Gemini表面活性剂对BSA的二级结构起两种相反的作用：在浓度较低时,表面活性剂对BSA的二级结构起稳定作用,在高表面活性剂浓度时,以变性作用为主。动态光散射实验表明,Gemini表面活性剂与BSA的复合物在饱和结合时的流体力学半径随着连接基团碳原子数的增加而减小。本论文的主要创新点如下：1.合成了四种疏水尾链长度不同的烷基苯磺酸盐Gemini表面活性剂,并研究了它们的表面活性和应用性能,为此类表面活性剂的理论研究以及应用开发提供重要的基础数据。2.合成了四种连接基团长度不同的烷基硫酸盐Gemini表面活性剂,并研究了它们的表面活性和应用性能,丰富了阴离子Gemini表面活性剂结构-性能关系的研究内容,为其应用奠定基础。3.首次研究了硫酸盐类Gemini表面活性剂与BSA的相互作用,探讨了连接基团长度对它们的相互作用的影响。通过多种实验方法分析测试和相互验证,提出了可能的作用机理。更多还原

【Abstract】 Gemini surfactants are a novel class of surfactants, which could be considered as dimers or oligomers of conventional surfactants with single headgroup and single hydrophobic tail. Compared with conventional surfactants, Gemini surfactants show better surface activity and richer aggregation behaviors, and the structures of Gemini surfactants are also more adjustable than conventional surfactants. Owing to their excellent properties, Gemini surfactants have attracted worldwide attention in the field of colloid and surface science over the past decades. Anionic surfactants, especially alkylbenzene sulfonate and alkyl sulfate surfactants, have been widely used in the fields of industrial production and academic research. Design and synthesis of new types of alkylbenzene sulfonate and alkyl sulfate Gemini surfactants and study of the structure-performance relationship of these surfactants, have become an important part in the field of surfactant science.Surfactants and polymers are often used together in practical applications. Proteins are an important kind of biomacromolecules. Protein-surfactant systems are widely used in the fields of detergents industry, cosmetics, bioscience, pharmaceutics and food. Thus studies on interactions of proteins and surfactants become very important. In this paper, two types of anionic Gemini surfactants, i.e. the alkylbenzene sulfonate type and the alkyl sulfate type, have been synthesized, and their aurface active properties and the interactions with bovine serum albumin (BSA) have been studied. The main contents of the thesis are as follows:1. The synthesis and properties of Gemini surfactants and their interactions with BSA were briefly reviewed.2. Four alkylbenzene sulfonate gemini surfactants with different alkyl tail length were synthesized based on long chain alkyl carboxylic acid, aniline and1,6-hexamethylene diisocyanate. The structures of the products were confirmed by FT-IR,1H NMR and ESI-MS.3. Four alkyl sulfate Gemini surfactants with different spacer length were synthesized based on1-bromodecane, diethyl malonate and dibromoalkane. The structures of the products were confirmed by FT-IR,1H NMR and ESI-MS.4. The surface active and micellization properties of the alkylbenzene sulfonate Gemini surfactants were investigated by means of surface tension, electrical conductivity and fluorescence measurements. The results showed that the cmc of these compounds were one or two orders of magnitude lower than the corresponding monomeric surfactant. There was an initial decrease and then an increase in cmc with the increase of hydrophobic alkyl tail. Molar conductivity measurement revealed the existence of premicellar aggregates in solutions of Gemini IV. Fluorescence probing studies showed that the micropolarities of these Gemini micelles varied little with the increase in alkyl tail length. Performance properties of these surfactants were also studied; low foamability, foam stability and wetting ability but good lime soap dispersing ability were observed for these compounds, the emulsifying power of the Geminis was also better than that of sodium dodecylbenzene sulfonate.5. The surface active and micellization properties of the alkyl sulfate Gemini surfactants were investigated by means of surface tension, electrical conductivity and fluorescence measurements. The cmc values obtained by the conductivity method were considerably higher than those obtained by the surface tension method, and comparable with those obtained by the fluorescence probing method. Molar conductivity measurement revealed the existence of premicellar aggregates for these surfactants, the formation of premicellar aggregates may account for the discrepancy between the cmc obtained by these different methods. In these cases, the traditional cmc refer to the values obtained by the conductivity method. The cmc values of these Gemini surfactants decreased monotonously with the increase of spacer chain length from3to10. The foamability and wetting ability of alkyl sulfate Geminis were lower than those of SDS, but the foam stability, emulsifying power and lime soap dispersing ability were better than those of SDS.6. The interactions of alkylbenzene sulfonate Gemini surfactants with BSA were studied by means of fluorescence, UV-Vis absorption spectroscopy and circular dichroism (CD). Fluorescence probing studies revealed that the micropolarities of Gemini-BSA complexes showed little difference with the variation of alkyl tail length. The micropolarities of gemin-BSA complexes at high surfactant concentration range were close to those of free Gemini micelles. Synchronous fluorescence spectra displayed that Geminis mainly interacted with the tryptophan residues of BSA. BSA intrinsic fluorescence spectra illustrated that the addition of Gemini surfactants to BSA solution resulted in quenching of BSA fluorescence intensity. The quenching process contained a mixture of dynamic and static quenching. At low concentration range, the quenching constant demonstrated an initial increase and then a decrease with the increase in alky tail length, this is the result of two opposite factors, on the one hand, geminis with a shorter alkyl tail may be easier to approach the cavity and interact with the tryptophan residue in the cavity, on the other hand, geminis with a longer alkyl tail may interact stronger with BSA through hydrophobic interaction. CD experiment showed that changes in secondary structures occurred when Gemini surfactants were added to BSA, the a-helix content decreased and β-sheet content increased.7. The interactions of alkyl sulfate Gemini surfactants with BSA were studied by means of fluorescence, CD and dynamic light scattering (DLS). Fluorescence probing studies displayed that the micropolarities of Gemini-BSA complexes decreased with the increase of spacer carbon number n, and they were lower than those of the corresponding free Gemini micelles. BSA intrinsic and synchronous fluorescence spectra demonstrated that BSA probably went through an intermediate state upon denaturation by the addition of Gemini surfactant, and the intermediate has a stronger tendency to aggregate than native and partly denatured BSA. CD experiment showed that the alkyl sulfate Gemini surfactants played two opposite roles when interacted with BSA. At low Gemini/BSA molar ratios, Gemini surfactants could stabilize the secondary structure of BSA, while at higher molar ratios, Gemini mainly acted as denaturants. DLS experiment illustrated that the size of gemini-BSA complexes decreased with the increase in spacer chain length.The innovations of this work are as follows:1. Four alkylbenzene sulfonate Gemini surfactants with different alkyl tail length were synthesized. Their surface active and performance properties were investigated. This provides basic scientific data for theoretical research and application studies.2. Four alkyl sulfate Gemini surfactants with different spacer length were synthesized. Their surface active and performance properties were investigated. This research enriches the studies about the structure-performance relationships of Gemini surfactants and lays the foundations for practical applications.3. The interactions of alkyl sulfate Gemini surfactants with BSA were first studied. The influence of spacer length on the interactions was discussed. The possible mechanism of interaction was proposed based on multi-technique experimental results.更多还原