納米粒子跨膜運(yùn)輸動力學(xué)機(jī)理研究
發(fā)布時間：2018-10-19 19:07
【摘要】：生物膜作為細(xì)胞的天然屏障,能選擇性調(diào)控物質(zhì)的跨膜運(yùn)輸,參與細(xì)胞的胞吞、胞吐、信號傳導(dǎo)等重要細(xì)胞活動。因此,研究物質(zhì)跨膜運(yùn)輸?shù)膭恿W(xué)過程對細(xì)胞生物學(xué)乃至生物醫(yī)藥應(yīng)用都具有重要的價值。近年來,隨著計算機(jī)技術(shù)的迅猛發(fā)展,分子模擬技術(shù)凸顯優(yōu)勢,能夠?qū)崿F(xiàn)對生物膜體系的相關(guān)研究�；诖吮菊撐牟捎梅肿觿恿W(xué)模擬方法,以納米粒子跨膜運(yùn)輸?shù)膭恿W(xué)過程為研究對象,對不同性質(zhì)的納米粒子跨膜運(yùn)輸?shù)臋C(jī)理進(jìn)行了系統(tǒng)而詳細(xì)的研究。本論文的主要研究內(nèi)容和創(chuàng)新點(diǎn)如下1納米粒子的形狀對其內(nèi)吞動力學(xué)的影響。研究了長圓柱形狀、短圓柱形狀、圓盤形狀以及球形納米粒子的內(nèi)吞動力學(xué)過程,發(fā)現(xiàn)旋轉(zhuǎn)是形狀各向異性的納米粒子內(nèi)吞過程的一個重要特征。通常納米粒子的內(nèi)吞過程分為兩個階段：下陷階段和包裹階段。在下陷過程中,為了促進(jìn)配受體的結(jié)合,納米粒子會通過旋轉(zhuǎn)實(shí)現(xiàn)和細(xì)胞膜接觸面積最大化。在包裹過程中,為了克服較小的彎曲能,細(xì)胞膜會進(jìn)一步調(diào)節(jié)納米粒子發(fā)生旋轉(zhuǎn)。因此不同形狀的納米粒子在兩個階段均具有各自最適宜的下陷角度和包裹角度。研究結(jié)果表明形狀各向異性的納米粒子還會誘發(fā)膜的非對稱性包裹內(nèi)吞。2納米粒子的表面配體分布對其穿膜的影響。設(shè)計了三種不同配體圖案(即,條紋圖案的、補(bǔ)丁圖案的以及隨機(jī)圖案)的納米粒子并研究了它們的穿膜行為。發(fā)現(xiàn)當(dāng)納米粒子的尺寸和親疏水配體比例相同時,親水配體以較分散的方式分布在納米粒子表面能有效降低納米粒子的穿膜能壘,提高納米粒子的穿膜能力。而對于多個親水條紋帶較寬的納米粒子共同穿膜時,容易誘發(fā)細(xì)胞膜的破裂,進(jìn)而產(chǎn)生細(xì)胞毒性。3納米粒子的硬度對其內(nèi)在化路徑的影響。我們設(shè)計了三種不同硬度的納米粒子(即,聚合物、脂質(zhì)體、以及剛性的納米粒子),并研究其內(nèi)在化的機(jī)理。結(jié)果顯示剛性的納米粒子能以內(nèi)吞的方式進(jìn)入細(xì)胞,而軟的納米粒子的內(nèi)吞路徑卻受受到了限制。因?yàn)檐浀募{米粒子在內(nèi)吞過程中容易變形且配體容易分布不均勻。軟的納米粒子主要是以穿膜的方式進(jìn)入細(xì)胞,且在穿膜過程中伴隨著親疏水片段的重排。4納米粒子的帶電性質(zhì)對其與生物膜相互作用的影響。(1)不同帶電圖案的納米粒子在生物膜表面的聚集。設(shè)計了5種不同帶電圖案的納米粒子。研究發(fā)現(xiàn)納米粒子的尺寸和帶電圖案都會影響其聚集行為。結(jié)果顯示由靜電作用誘發(fā)的納米粒子的聚集需要最小的有效帶電區(qū)域。當(dāng)納米粒子表面局部帶電區(qū)域小于有效的帶電區(qū)域時,則不能誘發(fā)納米粒子的聚集。此外,納米粒子表面的帶電圖案也會影響納米粒子的聚集結(jié)構(gòu)。因此對于不同的生物應(yīng)用,可以通過調(diào)節(jié)納米粒子表面的電荷分布,實(shí)現(xiàn)對納米粒子聚集形式的調(diào)控。(2)膜電勢對帶電納米粒子在細(xì)胞膜表面的粘附的影響。在真實(shí)細(xì)胞中,細(xì)胞膜內(nèi)外常常存在膜電勢,為此我們研究了膜電勢對帶電納米粒子在細(xì)胞膜表面的粘附的影響。研究結(jié)果發(fā)現(xiàn)降低膜電勢,會使陰離子納米粒子在生物膜表面的粘附數(shù)量減少,而對陽離子納米粒子在生物膜表面的粘附影響不大。這主要是由于陰離子納米粒子在生物膜表面的粘附主要是膜電勢誘導(dǎo)的,而陽離子納米粒子在生物膜表面的粘附主要是受膜表面帶負(fù)電的膜蛋白的作用。(3)多個帶電納米粒子的內(nèi)吞路徑。研究發(fā)現(xiàn)雖然同種電荷的納米粒子之間存在靜電排斥力,但仍然以協(xié)同的方式被膜共同包裹內(nèi)吞。這主要是由膜的彎曲能誘發(fā)的同種電荷納米粒子之間的吸引。同時,帶電納米粒子的內(nèi)吞路徑主要受到納米粒子的尺寸、納米粒子表面帶電配體的密度、以及納米粒子間的距離的影響。對于多個小尺寸的帶電納米粒子,主要是以協(xié)同內(nèi)吞的方式進(jìn)入細(xì)胞。而對于大尺寸的帶電納米粒子,納米粒子能否協(xié)同內(nèi)吞取決于納米粒子帶電配體的密度以及納米粒子之間的初始間距。5具有高效穿膜能力的穿膜聚合物的設(shè)計�；谝陨系难芯恳约敖Y(jié)合穿膜肽親疏水的結(jié)構(gòu)特性,我們設(shè)計出一種高效的穿膜聚合物。其中穿膜聚合物具有親疏水間隔的鏈狀結(jié)構(gòu)。當(dāng)穿膜聚合物的疏水片段長度接近膜厚時,其具有高效的穿膜能力。穿膜聚合物的穿膜方式主要是：“拉鏈?zhǔn)健焙汀皡f(xié)同方式”。通過將穿膜聚合物嫁接在親水藥物表面,發(fā)現(xiàn)穿膜聚合物能有效的協(xié)助親水藥物穿透生物膜。6膜蛋白的聚集機(jī)理。膜蛋白作為生物膜的重要組成部分,對物質(zhì)的運(yùn)輸,信號的傳導(dǎo),膜的變形等起著重要的作用。為此,我們研究了膜蛋白的聚集機(jī)理。繼“親疏水不匹配”聚集機(jī)理和“靜電作用”聚集機(jī)理之后,提出膜蛋白“形狀的互補(bǔ)性”也是誘發(fā)其聚集的一個重要原因。當(dāng)形狀互補(bǔ)的兩個膜蛋白相互靠近時,膜蛋白之間的磷脂的構(gòu)型熵會受到限制,因此磷脂會趨于離開膜蛋白之間的狹縫區(qū)域,而等效地誘導(dǎo)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，
本文編號：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，
本文編號：2282095
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