纳米气泡生长的界面调控及其对蛋白活性的影响研究

发布时间：2018-05-17 15:35

  本文选题：纳米气泡 + 原子力显微镜(AFM)　； 参考：《中南林业科技大学》2017年硕士论文

【摘要】：纳米尺度下气体在固液界面上的聚集行为被证明对固液界面性质有着重要的影响,并且在流体动力学、表面化学、胶体化学、环境和生命科学等众多领域具有广阔的潜在应用价值,引起了科学工作者极大的关注和重视。关于如何解释界面纳米气泡的稳定存在机理以及相比于宏观尺度下较大的接触角是目前纳米气泡研究的争议中心和亟需解决的核心问题。界面纳米气泡的研究离不开基底。从理论上讲,上述两个关键问题都直接涉及产生纳米气泡的基底,因此基底的性质是影响纳米气泡界面性质不可忽略的关键因素之一。一方面,气泡在不同基底上的形成,稳定性以及界面形貌都可能不同;另一方面,受基底性质的影响,不同的基底得到的纳米气泡的接触角也可能不一样。但目前各个实验组研究的基底都相对单一,生成纳米气泡的大小和数量的可控性和重复性差,所以,迫切需要找到一种通过控制基底的界面结构和性质来控制纳米气泡的大小和数量的方法来进一步研究纳米气泡的基本物理性质,形成机理和稳定机制等关键问题。基于以上目的,本论文利用先进的微纳米加工技术—电子束光刻(Electron Beam Lithography,EBL)直写技术制备不同尺度、和不同疏水性的纳米周期性结构基底。通过先进的纳米观测技术—原子力显微镜(Atom Force Microscopy,AFM)技术对纳米气泡在周期性结构基底上的吸附行为和界面特性的研究发现纳米气泡主要吸附于周期性结构上的疏水区域且受限于疏水结构的尺寸进而引起接触角的变化。与此同时,相应的分子动力学模拟也进一步证实了疏水结构对纳米气泡的限制作用,使得实验与模拟能够相互印证,相互支持。这将为实现通过基底的性质来人为调控纳米气泡的生成和界面吸附的目的,为探索纳米气泡在微流体器件方面的应用提供实验基础。生理惰性气体进入人体后与一些生物分子或者离子通道结合进而对许多生命过程发挥着重要的作用,如生物麻醉,神经、组织保护等,然而人们对其内在的作用机理却是知之甚少。分子动力学研究发现聚集态的氮气分子可以特异性地与蛋白的活性位点结合,而游离的氮气分子却不具有这一特异性结合效应。随着纳米气泡的发现,这似乎为我们提出了一个新的思路。惰性气体分子能够在蛋白分子的疏水基团发生特异性结合形成气泡从而使得这些基团的生物功能被屏蔽失效,当气体被清除掉后,相应的生物功能可能会恢复。基于这一设想,我们通过上海光源BL15U同步辐射硬X射线荧光吸收谱和荧光成像技术对Xe和Kr在胃蛋白酶上的吸附情况进行了研究,结果表明Xe和Kr在含胃蛋白酶的溶液中的含量都比不含胃蛋白酶的水溶液高。纳米粒子追踪实验结果表明含Xe的胃蛋白酶溶液中的粒子浓度比不含Xe的胃蛋白酶溶液高,这可能是由于Xe分子与胃蛋白酶结合形成较大粒子进而被捕获。分子动力学结果表明,不同的气体分子可以在胃蛋白酶分子上特异性地聚集为气泡。相关的蛋白活性实验也表明加入N2,Xe,Kr的胃蛋白酶溶液,其蛋白活性降低,经脱气处理后,蛋白活性恢复。这就为我们深入理解气体分子的生物效应提供了新的思路。
[Abstract]:The aggregation behavior of gas on the solid-liquid interface in nanoscale has been proved to have an important influence on the properties of the solid-liquid interface, and has a broad potential application value in many fields, such as hydrodynamics, surface chemistry, colloid chemistry, environment and life science. It has aroused great attention and attention of the scientific workers. The stable existence mechanism of the surface nanoscale and the larger contact angle compared to the macro scale are the center of dispute and the key problem to be solved at present. The research on the interface nanoscale can not be separated from the substrate. In theory, the above two key problems are directly related to the formation of the basement of the nanoscale bubble, so the base Property is one of the key factors that can not be ignored. On the one hand, the formation, stability and interface morphology of bubbles may be different on different substrates. On the other hand, the contact angles of different substrates may be different by the effect of substrate properties. As the substrate is relatively single, the size and quantity of the nano bubbles are controlled and the reproducibility is poor. Therefore, it is urgent to find a method to control the size and quantity of the nanoscale by controlling the interface structure and properties of the substrate to further study the basic physical properties, the formation mechanism and the stability mechanism of the nanoscale. Based on the above purposes, this paper makes use of advanced micro nano processing technology, Electron Beam Lithography (EBL) direct writing technique to prepare different scales and different hydrophobicity nanoscale periodic structure substrates. By advanced nano observation technology, atomic force microscopy (Atom Force Microscopy, AFM) technology for nano bubbles The study on the adsorption behavior and interfacial properties on the periodic structure shows that the nano bubbles are mainly adsorbed on the hydrophobic region on the periodic structure and are limited to the size of the hydrophobic structure and then cause the change of the contact angle. At the same time, the corresponding molecular dynamics simulation also further confirms the limitation of the hydrophobic structure to the nanoscale. The experiment and simulation can confirm each other and support each other. This will provide an experimental basis for the purpose of realizing the formation and adsorption of nano bubbles by the nature of the substrate, and to explore the application of the nano bubbles in the micro fluid devices. It also plays an important role in many life processes, such as biological anaesthesia, nerve, tissue protection, and so on. However, people know little about its intrinsic mechanism. Molecular dynamics studies find that the nitrogen molecules in the aggregation state can specifically combine with the active sites of the protein, while the free nitrogen molecules do not have this one. Specific binding effect. With the discovery of nanoscale, this seems to give us a new idea. The inert gas molecules can specifically bind to the hydrophobic groups of the protein molecules to form bubbles so that the biological functions of these groups are shielded and invalidation. When the gas is removed, the corresponding biological function may be restored. Based on this idea, we have studied the adsorption of Xe and Kr on pepsin by BL15U synchrotron radiation hard X ray fluorescence absorption spectrum and fluorescence imaging technology of the Shanghai light source. The results show that the content of Xe and Kr in the solution containing pepsin is higher than that without pepsin aqueous solution. The concentration of Xe in pepsin solution is higher than that of a pepsin solution without Xe, which may be due to the formation of larger particles of Xe molecules with pepsin and then captured. Molecular dynamics results show that different gas molecules can specifically gather as bubbles on the pepsin molecules. Related protein activity experiments It also showed that the protein activity of pepsin solution in N2, Xe and Kr was reduced, and the activity of protein was restored after degassing, which provided a new idea for us to understand the biological effects of gas molecules.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q68
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本文编号：1901898