高分子链穿越折线型纳米孔与平面上多价态高分子链吸附的动力学

发布时间：2018-04-25 12:24

本文选题：朗之万动力学 + 折线型纳米孔　；参考：《中国科学技术大学》2015年硕士论文

【摘要】：在实际的材料应用过程中和生物体内,高分子的受限都是一个非常普遍的现象。高分子的受限行为可以分为一维受限、二维受限和三维受限三个类型。近年来,高分子在受限环境中的动力学和构象受到了广泛而深入的研究。一方面,它能够帮助我们更好地理解许多生物学现象；另一方面,它在某些前沿的科技领域有着光明的应用前景,比如,高分子穿越纳米孔道动力学的研究对下一代基因测序技术的发展就起着至关重要的作用。本文采用计算机模拟的方法,对高分子穿越折线型纳米孔道的动力学和含有多配体高分子链的吸附动力学和构象进行了研究。下一代基因测序技术发展的一个关键问题是,如何有效地降低DNA的穿孔速率,使DNA上的碱基单元能够一个一个的穿过纳米孔,从而可以被准确的检测出来。本文的第三章中,应用二维朗之万动力学的模拟方法,我们对外加电场力驱动下高分子链穿越折线型纳米孔道的动力学行为进行了研究。由于高分子链和孔道墙粒子存在着较强的相互作用力,因此,和穿越直线型纳米孔道相比,高分子链穿越折线型纳米孔道的动力学有显著的变化。在模拟中,我们采用了五种不同的折线型纳米孔道,每一种类型的纳米孔都对应着一个弯曲角θ。我们对高分子链的穿孔时间和穿孔成功率与θ的变化关系进行了研究。和直孔相比,折线型纳米孔的穿孔时间会随着θ角的增大而显著的增长,穿孔速率得到了有效的降低,这个结果跟之前的实验是相一致的。本文的第四章,我们对含有多个配体的高分子链在含有多个受体的膜表面上的吸附行为进行了研究。早在1998年,哈佛大学的Mammen教授等人研究发现,多个相同配体-受体的相互作用普遍存在于生物体内,并提出了生物体内的多价态结合(multivalency)的理论。这个理论认为,生物分子或者生物表面之间的结合,是瞬时的多配体-受体的多价态作用的结果。尽管多种多配体高分子已经被合成出来并且对它的吸附行为进行了大量的实验研究,但是,多价态理论的物理机理依然不明确。Frenkel教授等人研究发现,多配体高分子链或者是多配体纳米粒子,对含有多个吸附位点的膜的吸附具有选择的特性。我们的研究结果,跟他们的理论和实验工作是相吻合的。除此之外,我们发现,对于Φ=0.20的链,当平面的受体密度φ增大的时候,高分子链的均方末端的会出现一个极大值。当链上的配体密度增加到0.34的时候,极值点所对应的φ会减小。分子链的尺寸和链长也是有一定的标度关系的。标度指数会随着φ的增大而减小。随着φ的增加,吸附达到平衡所需要的时间会逐渐减少。但是,当φ增大到一定程度的时候,吸附达到平衡所需要的时间将不再随着φ的增大而降低。
[Abstract]:The limitation of polymer is a very common phenomenon in practical material application and in vivo. The confined behavior of polymer can be divided into three types: one dimensional confinement, two dimensional confinement and three dimensional confinement. In recent years, the dynamics and conformation of polymers in confined environments have been extensively and deeply studied. On the one hand, it can help us better understand many biological phenomena; on the other hand, it has a bright future in some cutting-edge fields of science and technology, such as, The study of the kinetics of polymer traversing nanochannels plays an important role in the development of the next generation gene sequencing technology. In this paper, the kinetics of polymer traversing the broken nanorods and the adsorption kinetics and conformation of polymer chains containing polyligand have been studied by computer simulation. One of the key problems in the development of next generation gene sequencing technology is how to effectively reduce the perforation rate of DNA so that the base units in DNA can pass through the nano-pores one by one and can be accurately detected. In the third chapter, we study the dynamic behavior of polymer chains passing through broken nanorods driven by electric field forces by using two-dimensional Langevin dynamics simulation method. Because of the strong interaction between polymer chains and pore wall particles, the kinetics of polymer chains passing through broken line nanochannels has a significant change compared with that of linear nanochannels. In the simulation, five different broken nanorods are used, and each type of nano-pore corresponds to a bending angle 胃. We have studied the relationship between the perforation time and the success rate of the polymer chain and theta. Compared with the straight hole, the perforation time increases significantly with the increase of 胃 angle, and the perforation rate decreases effectively, which is consistent with previous experiments. In chapter 4, we study the adsorption behavior of polymer chains containing multiple ligands on the surface of membranes containing multiple receptors. As early as 1998, Professor Mammen et al of Harvard University found that the interaction of multiple identical ligands and receptors existed generally in organisms, and put forward the theory of multivalency binding in organisms. This theory suggests that the binding between biomolecules or biological surfaces is the result of the transient multivalent interaction of multiple ligand receptors. Although a variety of polyligand polymers have been synthesized and their adsorption behavior has been studied in many experiments, the physical mechanism of the polyvalent state theory is still unclear. Polyligand polymer chains or polyligand nanoparticles have selective adsorption properties for membranes with multiple adsorption sites. Our results agree with their theoretical and experimental work. In addition, we find that for the chain with 桅 0. 20, a maximum of the mean square end of the polymer chain will occur when the receptor density 蠁 increases in the plane. When the ligand density on the chain increases to 0.34, the 蠁 corresponding to the extreme point decreases. Molecular chain size and chain length also have a certain scale relationship. The scaling index decreases with the increase of 蠁. With the increase of 蠁, the time required for adsorption to reach equilibrium will gradually decrease. However, when 蠁 increases to a certain extent, the time required for adsorption to reach equilibrium will no longer decrease with the increase of 蠁.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O631.1

【共引文献】