核酸碱基手性表面活性剂的缔合行为及其与DNA的相互作用

发布时间：2019-06-26 21:14

【摘要】：手性表面活性剂能通过自组装形成各种结构的手性自组装体,在生物医药领域具有重要的应用价值,可以用于生物、药物的识别,制备靶向性的DNA纳米载体材料等。胸腺嘧啶型手性表面活性剂具有独特的分子结构,嘧啶环之间有较强的氢键作用和π-π堆积,并且氢键对环境有较强的敏感性。因此研究该表面活性剂手性聚集体行为和作用机理,以及其与DNA的复合作用的缔合模式,不仅从分子的水平理解手性自组装的缔合特性,更有望拓展手性表面活性剂的应用,发展更多功能性的手性自组装体材料。基于以上目标,本文主要进行了如下的研究工作：1、设计合成了三种不同链长的手性嘧啶型表面活性剂(8-(1-胸腺嘧啶基)辛基)三甲基溴化铵,(10-(1-胸腺嘧啶基)癸基)三甲基溴化铵和(12-(1-胸腺嘧啶基)十二烷基)三甲基溴化铵,简称为T-Cn-TAB (n=8,10,12),以傅立叶变换红外光谱、核磁共振和元素分析等手段对其结构进行表征,同时利用表面张力、电导率等方法研究了该类手性表面活性剂在水溶液中的表面活性。结果表明,所合成的物质均为实验所需的目标产物,纯度较高,符合实验要求。并且,随着T-Cn-TAB (n=8,10,12)链长的增加,临界胶束浓度(cmc)逐渐降低,γcmc最低可达到47.2 mN/m。圆二色谱的测定表明,在230nm-290 nm处发现较大的负吸收,证实手性自组装体的存在。2、通过电导率法、等温滴定微量热法、1HNMR、2D NOESY、动态光散射、负染透射电镜和密度泛函理论计算等一系列手段对T-Cn-TAB (n=8,10,12)在水溶液中的胶束化行为进行了系统研究。研究发现,手性嘧啶型表面活性剂在水中的缔合是一个含驱动的自组装行为,反应的热效应ΔHmic0在-10.7kJ/mol,且随T升高,反应的热效应逐步增加。动态光散射表明手性聚集体的水合流体力学半径在0.7 nm左右,透射电镜表明这种手性聚集体为尺寸均一,分散性良好的球形聚集体。1HNMR和2D NOESY的结果表明在形成手性胶束的过程中,胸腺嘧啶基的嘧啶环处于胶核内部并且相邻的嘧啶环之间形成π-π堆积,平行排列于其中,得到结构紧密的胶束聚集体。密度泛函理论计算进一步证实上述的聚集体中分子的紧密排列方式。并且,升高温度,聚集体的尺寸与手性信号都发生了改变,这可能由于温度的改变使得氢键发生断裂,从而改变了聚集体的构型。3、以电导率法、荧光光谱、动态光散射、低温透射电子显微镜圆二色谱法等研究了核酸碱基型表面活性剂T-C12-TAB与DNA相互作用特性和分子间的缔合机理。电导率法结果表明DNA存在时,T-C12-TAB的电导率略有增加,表明T-C12-TAB与DNA之间发生了缔合作用。基于探针溴化乙锭(EtBr)的荧光测定表面,随着T-C12-TAB浓度的增加,DNA-EtBr的荧光强度逐渐增加。这与通常加入离子液体表面活性剂和传统表面活性剂的行为正好相反。这表明手性嘧啶型表面活性剂与DNA具有独特的缔合特性。动态光散射测定表面DNA/T-C12-TAB复合物的流体力学半径也从220 nm增加为360 nm左右,进一步表明尽管手性表面活性剂与DNA之间有电荷吸引作用但手性嘧啶型表面活性剂与DNA存在着独特的缔合作用,也验证了其荧光特性。圆二色谱表明在作用的过程中,B-型DNA的结构基本保持不变,但其碱基部分转变,进一步验证了上述结果。初步认为是胸腺嘧啶环与DNA的碱基对之间有较强的氢键作用和疏水作用,使得表面活性剂处于DNA螺旋结构的沟槽中,使其尺寸变大。
[Abstract]:The chiral surfactant can form a chiral self-assembly of various structures by self-assembly, has important application value in the field of biological medicine, and can be used for the identification of a biological and a medicament, and the preparation of a targeted DNA nano-carrier material and the like. The thymosin-type chiral surface active agent has a unique molecular structure, and has a strong hydrogen bonding effect and a gas-hydrogen bond accumulation between the dendritic rings, and the hydrogen bond has a strong sensitivity to the environment. therefore, the behavior and the action mechanism of the chiral aggregate of the surface active agent and the association mode of the compound action of the surface active agent and the DNA are researched, the association characteristic of the chiral self-assembly is not only understood from the level of the molecule, the application of the chiral surfactant is more likely to be expanded, Development of more versatile chiral self-assembly materials. Based on the above objectives, the following research work is carried out in this paper:1. The three different chain lengths of chiral dendritic surface active agents (8-(1-thymic-base) octyl) trimethylammonium bromide are designed and synthesized. (10-(1-thymic-base) decyl) trimethylethidium bromide and (12-(1-thymic-base) dodecyl) trimethylammonium bromide, abbreviated as T-Cn-TAB (n = 8,10,12), characterized by means of Fourier transform infrared spectroscopy, nuclear magnetic resonance and elemental analysis, while using surface tension, The surface activity of this kind of chiral surfactant in aqueous solution was studied by electric conductivity. The results showed that the synthesized materials were the desired product of the experiment and the purity was high, and it was in accordance with the requirements of the experiment. In addition, with the increase of the chain length of T-Cn-TAB (n = 8,10,12), the critical micelle concentration (cmc) is gradually reduced, and the critical micelle concentration (cmc) can reach 47.2 mN/ m. The determination of the circular dichroism showed that a large negative absorption was found at 230 nm to 290 nm, and the presence of the chiral self-assembled body was confirmed.2. By the method of electric conductivity, the microthermal method of isothermal titration, 1HNMR, 2D NOESY, dynamic light scattering, The micellar behavior of T-Cn-TAB (n = 8,10,12) in aqueous solution was studied by a series of methods such as negative-staining transmission electron microscopy (TEM) and density functional theory (DFT). It has been found that the association of the chiral dendritic surface active agent in water is a self-assembled behavior with a drive, the thermal effect of the reaction is Hmicro at-10.7 kJ/ mol, and with the rise of T, the thermal effect of the reaction is gradually increased. The dynamic light scattering indicates that the hydrodynamic radius of the chiral aggregate is about 0.7 nm, and the transmission electron microscope shows that the chiral aggregate is a spherical aggregate with uniform size and good dispersibility. The results of 1H NMR and 2D NOESY show that in the process of forming the chiral micelles, The ring-like ring of the thymosin group is in the inner part of the rubber core and is formed between the adjacent ring-shaped ring and the ring-shaped ring, and is arranged in parallel to obtain the close-structure micelle aggregate. The density functional theory calculation further confirms the close arrangement of the molecules in the above-mentioned aggregates. and the temperature, the size of the aggregate and the chiral signal have changed, which may cause the hydrogen bond to break due to a change in temperature, thereby changing the configuration of the aggregate.3, using the conductivity method, the fluorescence spectrum, the dynamic light scattering, The interaction of T-C12-TAB with DNA and the association mechanism of the nucleic acid base type surface active agent T-C12-TAB and DNA were studied by low-temperature transmission electron microscope. The results showed that the conductivity of T-C12-TAB increased slightly in the presence of DNA, indicating the association between T-C12-TAB and DNA. The fluorescence intensity of DNA-EtBr increased with the increase of T-C12-TAB concentration, based on the fluorescence measurement of the probe ethidium bromide (EtBr). This is in contrast to the behavior of the usual addition of ionic liquid surfactants and conventional surfactants. This indicates that the chiral dendritic surfactant and the DNA have unique association properties. The hydrodynamic radius of the surface DNA/ T-C12-TAB complex was also increased from 220 nm to about 360 nm. Its fluorescence characteristics were also verified. In the process of action, the structure of B-type DNA is basically unchanged, but the base part of the B-type DNA is changed, and the above results are further verified. It is believed that there is a strong hydrogen bond and a hydrophobic interaction between the base pair of the thymosin ring and the DNA, so that the surface active agent is in the groove of the DNA spiral structure, and the size thereof is increased.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：Q523;O647.2

【相似文献】