纳米粒子跨膜运输动力学机理研究
发布时间：2018-10-19 19:07
【摘要】：生物膜作为细胞的天然屏障,能选择性调控物质的跨膜运输,参与细胞的胞吞、胞吐、信号传导等重要细胞活动。因此,研究物质跨膜运输的动力学过程对细胞生物学乃至生物医药应用都具有重要的价值。近年来,随着计算机技术的迅猛发展,分子模拟技术凸显优势,能够实现对生物膜体系的相关研究。基于此本论文采用分子动力学模拟方法,以纳米粒子跨膜运输的动力学过程为研究对象,对不同性质的纳米粒子跨膜运输的机理进行了系统而详细的研究。本论文的主要研究内容和创新点如下1纳米粒子的形状对其内吞动力学的影响。研究了长圆柱形状、短圆柱形状、圆盘形状以及球形纳米粒子的内吞动力学过程,发现旋转是形状各向异性的纳米粒子内吞过程的一个重要特征。通常纳米粒子的内吞过程分为两个阶段：下陷阶段和包裹阶段。在下陷过程中,为了促进配受体的结合,纳米粒子会通过旋转实现和细胞膜接触面积最大化。在包裹过程中,为了克服较小的弯曲能,细胞膜会进一步调节纳米粒子发生旋转。因此不同形状的纳米粒子在两个阶段均具有各自最适宜的下陷角度和包裹角度。研究结果表明形状各向异性的纳米粒子还会诱发膜的非对称性包裹内吞。2纳米粒子的表面配体分布对其穿膜的影响。设计了三种不同配体图案(即,条纹图案的、补丁图案的以及随机图案)的纳米粒子并研究了它们的穿膜行为。发现当纳米粒子的尺寸和亲疏水配体比例相同时,亲水配体以较分散的方式分布在纳米粒子表面能有效降低纳米粒子的穿膜能垒,提高纳米粒子的穿膜能力。而对于多个亲水条纹带较宽的纳米粒子共同穿膜时,容易诱发细胞膜的破裂,进而产生细胞毒性。3纳米粒子的硬度对其内在化路径的影响。我们设计了三种不同硬度的纳米粒子(即,聚合物、脂质体、以及刚性的纳米粒子),并研究其内在化的机理。结果显示刚性的纳米粒子能以内吞的方式进入细胞,而软的纳米粒子的内吞路径却受受到了限制。因为软的纳米粒子在内吞过程中容易变形且配体容易分布不均匀。软的纳米粒子主要是以穿膜的方式进入细胞,且在穿膜过程中伴随着亲疏水片段的重排。4纳米粒子的带电性质对其与生物膜相互作用的影响。(1)不同带电图案的纳米粒子在生物膜表面的聚集。设计了5种不同带电图案的纳米粒子。研究发现纳米粒子的尺寸和带电图案都会影响其聚集行为。结果显示由静电作用诱发的纳米粒子的聚集需要最小的有效带电区域。当纳米粒子表面局部带电区域小于有效的带电区域时,则不能诱发纳米粒子的聚集。此外,纳米粒子表面的带电图案也会影响纳米粒子的聚集结构。因此对于不同的生物应用,可以通过调节纳米粒子表面的电荷分布,实现对纳米粒子聚集形式的调控。(2)膜电势对带电纳米粒子在细胞膜表面的粘附的影响。在真实细胞中,细胞膜内外常常存在膜电势,为此我们研究了膜电势对带电纳米粒子在细胞膜表面的粘附的影响。研究结果发现降低膜电势,会使阴离子纳米粒子在生物膜表面的粘附数量减少,而对阳离子纳米粒子在生物膜表面的粘附影响不大。这主要是由于阴离子纳米粒子在生物膜表面的粘附主要是膜电势诱导的,而阳离子纳米粒子在生物膜表面的粘附主要是受膜表面带负电的膜蛋白的作用。(3)多个带电纳米粒子的内吞路径。研究发现虽然同种电荷的纳米粒子之间存在静电排斥力,但仍然以协同的方式被膜共同包裹内吞。这主要是由膜的弯曲能诱发的同种电荷纳米粒子之间的吸引。同时,带电纳米粒子的内吞路径主要受到纳米粒子的尺寸、纳米粒子表面带电配体的密度、以及纳米粒子间的距离的影响。对于多个小尺寸的带电纳米粒子,主要是以协同内吞的方式进入细胞。而对于大尺寸的带电纳米粒子,纳米粒子能否协同内吞取决于纳米粒子带电配体的密度以及纳米粒子之间的初始间距。5具有高效穿膜能力的穿膜聚合物的设计。基于以上的研究以及结合穿膜肽亲疏水的结构特性,我们设计出一种高效的穿膜聚合物。其中穿膜聚合物具有亲疏水间隔的链状结构。当穿膜聚合物的疏水片段长度接近膜厚时,其具有高效的穿膜能力。穿膜聚合物的穿膜方式主要是：“拉链式”和“协同方式”。通过将穿膜聚合物嫁接在亲水药物表面,发现穿膜聚合物能有效的协助亲水药物穿透生物膜。6膜蛋白的聚集机理。膜蛋白作为生物膜的重要组成部分,对物质的运输,信号的传导,膜的变形等起着重要的作用。为此,我们研究了膜蛋白的聚集机理。继“亲疏水不匹配”聚集机理和“静电作用”聚集机理之后,提出膜蛋白“形状的互补性”也是诱发其聚集的一个重要原因。当形状互补的两个膜蛋白相互靠近时,膜蛋白之间的磷脂的构型熵会受到限制,因此磷脂会趋于离开膜蛋白之间的狭缝区域,而等效地诱导膜蛋白的聚集。
[Abstract]:Biofilm acts as a natural barrier for cells, which can selectively regulate the cross-membrane transport of substances, and participate in important cell activities such as cellular uptake, exocytosis, signal transduction, and so on. Therefore, the study on the kinetics of cross-membrane transportation is of great value to cell biology and biological medicine application. In recent years, with the rapid development of computer technology, molecular simulation technology highlights the advantages and can realize the relevant research on the biological membrane system. Based on the molecular dynamics simulation method, the mechanism of cross-membrane transport of nano-particles with different properties was studied in detail by using the kinetic process of nano-particle cross-membrane transport as the research object. The main research contents and innovation points of this paper are as follows: the influence of the shape of the nano-particles on endocytic kinetics. In this paper, a long cylindrical shape, a short cylindrical shape, a disc shape and an endocytic kinetics process of spherical nanoparticles are studied, and it is found that rotation is an important feature of the process of nano-particles in shape anisotropy. Typically, the endocytic process of nanoparticles is divided into two stages: a sag phase and a wrapping phase. In the process of sagging, nanoparticles can be maximized by rotation and cell membrane contact in order to promote the binding of the receptors. In the process of wrapping, in order to overcome the small bending energy, the cell membrane further regulates the rotation of the nanoparticles. so that the nano particles of different shapes have the most suitable sinking angle and the wrapping angle at both stages. The results show that the nano-particles with anisotropic shape can also induce the asymmetric inclusion of the film and the influence of the distribution of the surface ligand on the membrane. Nanoparticles of three different ligand patterns (i.e., stripe patterns, patch patterns, and random patterns) were designed and their film-penetrating behavior was investigated. It is found that when the size of nano-particles and the proportion of lipophilic-hydrophobic ligands are the same, the hydrophilic ligands are distributed in a dispersed manner on the surface of the nanoparticles to effectively reduce the penetration resistance of the nanoparticles and improve the film-penetrating ability of the nanoparticles. However, it is easy to induce the rupture of the cell membrane when the nano-particles with wider hydrophilic stripe are coated with the film, so that the cytotoxicity of the nano-particles can be generated. We designed three different hardness nanoparticles (i.e., polymers, liposomes, and rigid nanoparticles) and studied their internalization mechanisms. The results show that the rigid nanoparticles enter the cells in such a way that the endocytic pathways of the soft nanoparticles are limited. because soft nanoparticles are easily deformed in the endocytic process and the ligand is easily distributed unevenly. The soft nano-particles enter the cells in the way of membrane-penetrating, and the rearrangement of the hydrophobic fragments is accompanied by the rearrangement of hydrophilic segments in the film-penetrating process. The influence of the charged properties of the nanoparticles on the interaction with the biofilm is studied. (1) aggregation of nano-particles of different charged patterns on the surface of the biological membrane. Five kinds of nano-particles with different charged patterns were designed. It was found that the size and charge pattern of nano-particles would affect its aggregation behavior. The results show that the aggregation of nanoparticles induced by electrostatic action requires a minimum effective charged region. the aggregation of nanoparticles cannot be induced when the local charged region of the surface of the nanoparticle is less than the active charged region. In addition, the charged patterns of the surface of the nanoparticles also affect the aggregation structure of the nanoparticles. therefore, for different biological applications, the charge distribution on the surface of the nano-particles can be adjusted, and the regulation of the aggregation form of the nano-particles can be realized. (2) The effect of membrane potential on the adhesion of charged nanoparticles on the surface of cell membranes. In real cells, membrane potential is often present inside and outside the cell membrane, and we have studied the effect of membrane potential on the adhesion of charged nanoparticles on the surface of cell membranes. The results of the study found that the reduction of membrane potential would reduce the number of adhesion of anionic nanoparticles on the surface of the biofilm, while the adhesion of cationic nanoparticles on the surface of the biofilm was not significant. This is mainly because the adhesion of the anionic nanoparticles on the surface of the biofilm is mainly induced by membrane potential, while the adhesion of the cationic nanoparticles on the surface of the biofilm is mainly influenced by negatively charged membrane proteins on the surface of the membrane. (3) an endocytic path of a plurality of charged nanoparticles. It was found that although there was electrostatic repulsion between the nanoparticles of the same charge, it was still swallowed by the membrane in a synergistic manner. this is primarily the attraction between the nano-particles of the same charge induced by the bending of the membrane. At the same time, the endocytic pathways of charged nanoparticles are mainly affected by the size of nanoparticles, the density of charged ligands on the surface of nanoparticles, and the distance between nanoparticles. For a plurality of small-sized charged nanoparticles, the cells are introduced primarily in a synergistic manner. For large-sized charged nanoparticles, the ability of nanoparticles to co-operate depends on the density of charged ligands of nanoparticles and the initial spacing between nanoparticles. Based on the above research and the structural characteristics of hydrophilic hydrophobic membrane, we designed a highly effective film-penetrating polymer. in which the film-through polymer has a chain-like structure with a hydrophobic spacing. When the length of the hydrophobic segment of the film-penetrating polymer is close to the film thickness, it has a high-efficiency through-film capability. The film-through mode of the film-penetrating polymer mainly comprises the following steps: 鈥淶ipper type鈥，
本文编号：2282095
[Abstract]:Biofilm acts as a natural barrier for cells, which can selectively regulate the cross-membrane transport of substances, and participate in important cell activities such as cellular uptake, exocytosis, signal transduction, and so on. Therefore, the study on the kinetics of cross-membrane transportation is of great value to cell biology and biological medicine application. In recent years, with the rapid development of computer technology, molecular simulation technology highlights the advantages and can realize the relevant research on the biological membrane system. Based on the molecular dynamics simulation method, the mechanism of cross-membrane transport of nano-particles with different properties was studied in detail by using the kinetic process of nano-particle cross-membrane transport as the research object. The main research contents and innovation points of this paper are as follows: the influence of the shape of the nano-particles on endocytic kinetics. In this paper, a long cylindrical shape, a short cylindrical shape, a disc shape and an endocytic kinetics process of spherical nanoparticles are studied, and it is found that rotation is an important feature of the process of nano-particles in shape anisotropy. Typically, the endocytic process of nanoparticles is divided into two stages: a sag phase and a wrapping phase. In the process of sagging, nanoparticles can be maximized by rotation and cell membrane contact in order to promote the binding of the receptors. In the process of wrapping, in order to overcome the small bending energy, the cell membrane further regulates the rotation of the nanoparticles. so that the nano particles of different shapes have the most suitable sinking angle and the wrapping angle at both stages. The results show that the nano-particles with anisotropic shape can also induce the asymmetric inclusion of the film and the influence of the distribution of the surface ligand on the membrane. Nanoparticles of three different ligand patterns (i.e., stripe patterns, patch patterns, and random patterns) were designed and their film-penetrating behavior was investigated. It is found that when the size of nano-particles and the proportion of lipophilic-hydrophobic ligands are the same, the hydrophilic ligands are distributed in a dispersed manner on the surface of the nanoparticles to effectively reduce the penetration resistance of the nanoparticles and improve the film-penetrating ability of the nanoparticles. However, it is easy to induce the rupture of the cell membrane when the nano-particles with wider hydrophilic stripe are coated with the film, so that the cytotoxicity of the nano-particles can be generated. We designed three different hardness nanoparticles (i.e., polymers, liposomes, and rigid nanoparticles) and studied their internalization mechanisms. The results show that the rigid nanoparticles enter the cells in such a way that the endocytic pathways of the soft nanoparticles are limited. because soft nanoparticles are easily deformed in the endocytic process and the ligand is easily distributed unevenly. The soft nano-particles enter the cells in the way of membrane-penetrating, and the rearrangement of the hydrophobic fragments is accompanied by the rearrangement of hydrophilic segments in the film-penetrating process. The influence of the charged properties of the nanoparticles on the interaction with the biofilm is studied. (1) aggregation of nano-particles of different charged patterns on the surface of the biological membrane. Five kinds of nano-particles with different charged patterns were designed. It was found that the size and charge pattern of nano-particles would affect its aggregation behavior. The results show that the aggregation of nanoparticles induced by electrostatic action requires a minimum effective charged region. the aggregation of nanoparticles cannot be induced when the local charged region of the surface of the nanoparticle is less than the active charged region. In addition, the charged patterns of the surface of the nanoparticles also affect the aggregation structure of the nanoparticles. therefore, for different biological applications, the charge distribution on the surface of the nano-particles can be adjusted, and the regulation of the aggregation form of the nano-particles can be realized. (2) The effect of membrane potential on the adhesion of charged nanoparticles on the surface of cell membranes. In real cells, membrane potential is often present inside and outside the cell membrane, and we have studied the effect of membrane potential on the adhesion of charged nanoparticles on the surface of cell membranes. The results of the study found that the reduction of membrane potential would reduce the number of adhesion of anionic nanoparticles on the surface of the biofilm, while the adhesion of cationic nanoparticles on the surface of the biofilm was not significant. This is mainly because the adhesion of the anionic nanoparticles on the surface of the biofilm is mainly induced by membrane potential, while the adhesion of the cationic nanoparticles on the surface of the biofilm is mainly influenced by negatively charged membrane proteins on the surface of the membrane. (3) an endocytic path of a plurality of charged nanoparticles. It was found that although there was electrostatic repulsion between the nanoparticles of the same charge, it was still swallowed by the membrane in a synergistic manner. this is primarily the attraction between the nano-particles of the same charge induced by the bending of the membrane. At the same time, the endocytic pathways of charged nanoparticles are mainly affected by the size of nanoparticles, the density of charged ligands on the surface of nanoparticles, and the distance between nanoparticles. For a plurality of small-sized charged nanoparticles, the cells are introduced primarily in a synergistic manner. For large-sized charged nanoparticles, the ability of nanoparticles to co-operate depends on the density of charged ligands of nanoparticles and the initial spacing between nanoparticles. Based on the above research and the structural characteristics of hydrophilic hydrophobic membrane, we designed a highly effective film-penetrating polymer. in which the film-through polymer has a chain-like structure with a hydrophobic spacing. When the length of the hydrophobic segment of the film-penetrating polymer is close to the film thickness, it has a high-efficiency through-film capability. The film-through mode of the film-penetrating polymer mainly comprises the following steps: 鈥淶ipper type鈥，
本文编号：2282095
本文链接：https://www.wllwen.com/kejilunwen/cailiaohuaxuelunwen/2282095.html
