【作者】 陈畅；

【导师】 沙菁(?)； 吕晓俊；

【作者基本信息】 东南大学 ， 机械设计及理论（专业学位）， 2021， 硕士

【摘要】 纳米孔技术是一种在单分子传感领域具有巨大前景的应用工具。但传统的纳米孔存在单一的单孔的结构和其材料本身的物理特性使其无法达到单原子精度的固有缺陷,极大地限制了其进一步的发展。本文提出一种串行纳米孔的结构,并探究其在DNA检测方面的应用潜力,聚焦于该串行孔系统本身的结构特性在DNA输运和过程的机理研究。为建立DNA的多孔迁移理论框架提供帮助。具体的研究内容及成果如下:(1)探究DNA在单层孔石墨烯纳米孔中易位特性。得出单层石墨烯纳米孔的开孔电流、纳米孔孔口处的电势降、水分子密度、离子的密度和流速关于纳米孔孔径变化规律。在DNA检测时,孔径是影响纳米孔测序的关键因素,越小的纳米孔会产生越大的堵塞电流比,并且延长其过孔时间。小于2.1nm的纳米孔会使双链DNA捕获变得困难甚至无法过孔。(2)建立串行石墨烯纳米孔DNA易位的分子动力学模型。对比分析了单孔和串行孔系统的开孔流体特性的差异。发现保证孔径一致的情况下,串行孔系统会使DNA捕获率和易位速度会减小,主要是由于串行孔系统另一个孔对电势的分担。另外,基于DNA通过第一个孔会对另一个孔附近的电势产生影响,第二个孔的孔径越小,反应越灵敏这一原理。研究还提出一种新的DNA检测方式,即通过测量第二个纳米孔两侧的跨膜电压来对第一个孔的DNA易位事件进行检测。(3)对离子在串行石墨烯纳米孔系统内的运动进行研究。发现当上层孔壁面原子带负电荷,下层带正电荷,在外加300m V电压下,中间腔体的流体中阴阳离子快速分离,泵出到两侧,留下不含盐离子的水。同时两侧溶液中电解质离子均无法通过该串行纳米孔。保持孔壁面电荷密度不变,增加纳米孔的数目会使离子泵出速率增大,而保持孔壁面电荷总量不变,增加纳米孔的数目则不会使泵出速率增加。在孔壁面电荷较大时,离子主要是从纳米孔边缘通过,随着孔表面电荷密度减小,通过区域逐渐转移到孔中心。更多还原

【Abstract】 Nanopore is a promising application tool in the field of single molecule sensing.However,the traditional nanopore have the inherent defects of single pore structure and the physical properties of the material itself,which make it impossible to achieve the accuracy of single atom,which greatly limits their further development.In this paper,we propose a serial nanopore structure and explore its application potential in DNA detection,focusing on the structural characteristics of the serial pore system itself in the mechanism of DNA transport and process.It is helpful to establish the theoretical framework of DNA porous migration.The contents and results are as follows:(1)Translocation characteristics of DNA in monolayer porous graphene nanopore were studied.The variation rules of the opening current,the potential drop,the density of water molecules,the density of ions and the flow velocity of the monolayer graphene nanopore were obtained.In DNA detection,pore size is a key factor affecting nanopore sequencing.The smaller the nanopore,the larger the blocking current ratio will be,and the longer the pore crossing time will be.Nanopore smaller than 2.1nm make it difficult or even impossible to capture double-stranded DNA through the pores.(2)The molecular dynamics model of DNA translocation in serial graphene nanopore was established.The fluid characteristics of single pore and serial pore systems are compared and analyzed.It was found that the DNA capture rate and translocation speed would decrease under the condition of the same pore size,mainly due to the sharing of potential by another pore in the serial pore system.In addition,based on the principle that DNA passing through the first hole will affect the electric potential near the other hole,the smaller the hole of the second hole,the more sensitive the response.We also propose a new DNA detection method,which measures the trans-membrane voltage on both sides of the second nanopore to detect the DNA translocation event in the first nanopore.(3)The movement of ions in a serial graphene nanopore system is studied.It is found that when the atoms on the upper hole wall are negatively charged and the atoms on the lower hole wall are positively charged,under the additional voltage of 300 m V,the cation and anion in the fluid of the intermediate cavity are rapidly separated and pumped out to the two sides,leaving the water without salt ions.At the same time,electrolyte ions on both sides of the solution could not pass through the serial nanopore.Increasing the number of nanopores will increase the ion pumping rate while keeping the charge density of the pore wall unchanged.However,increasing the number of nanopores will not increase the ion pumping rate while keeping the total charge of the pore wall unchanged.When the charge on the pore wall is high,the ions mainly pass through the edge of the nanopore,and gradually transfer through the region to the center of the pore with the decrease of the charge density on the pore surface.更多还原