单晶硅表面修饰及其纳米力学行为研究
发布时间：2018-10-05 14:10
【摘要】：基于纳米孔的第三代基因测序仪以及相关的关键技术对于保护我国自己的基因资源具有战略意义。要实现该类基因测序技术,目前存在的主要问题:一是DNA分子过孔速度过快,由于过孔速度过快,通过测试得到的过孔电流的特征来识别过孔的碱基还具有较大困难;二是四种碱基与生物纳米孔壁相互作用机理尚不清晰,进一步的研究表明,DNA碱基与纳米孔孔壁之间的相互作用力越大,那么纳流体中离子的热运动就越小,而噪声信号主要就来源于离子的热运动,增加DNA碱基与纳米孔壁之间的相互作用力有助于提高信噪比。因此研究DNA碱基与壁面的特异性作用对于第三代基因测序具有重大的意义。本文对DNA两种碱基的结构进行了分析,从机械特性出发,研究了单晶硅的纳米力学性能,并以单晶硅为基体材料,实现DNA碱基生物分子的组装,系统的研究修饰机理、固定率的影响因素以及受限条件下修饰表面的力学行为。表征结果表明,腺嘌呤分子A和胸腺嘧啶分子T均有区别于其他碱基的特征性谱峰。接触角测量结果显示,硅基体完全硅烷化的时间为30min左右;醛基化反应在20min时初次形成完整的分子膜,并随着时间延长逐层生长。DNA碱基链的活性氨基基团与硅基体表面的醛基基团发生反应从而固定在硅基体上。荧光试验结果表明,影响荧光背景强度的四个因素中,硅烷化试剂的浓度影响最大,硅烷化时间影响最小。当硅烷化和醛基化试剂浓度较低时,碱基A和碱基T的固定率随着时间的增加均呈现线性增长;当试剂浓度较大时,碱基A和碱基T的固定率均出现极大值。当探针的缓冲溶液pH为弱碱性时,碱基固定率较大;探针点样浓度为50μmol/L时固定率较高;在同一条件下碱基A固定率高于碱基T。单晶硅的纳米力学研究结果表明:对于既定的最大加载力,随着压头尖端半锥角的增大,单晶硅弹性回复率逐渐增大,而弹性回复量基本恒定;在同一实验条件下,相较于(100)晶面,单晶硅(111)晶面具有较小的硬度和弹性模量值;随着最大加载力的增加,单晶硅压痕周围材料会出现堆积和表面隆起现象,压痕的弹性回复量增大,塑性区的范围随着加载力的增大而增大,出现明显的尺寸效应。修饰面的力学行为研究结果表明:在大气环境下,对于10nm以上的间隙,探针与硅片表面法向作用力受表面化学形态影响较小;在7nm以下间隙,经碱基修饰后的表面与探针作用力明显减小,且探针与碱基A和碱基T的作用力受加载速率的影响较大。随着法向力的增加,探针与硅基体的横向作用力增加,摩擦系数逐渐减小;探针与不同修饰条件下硅片表面产生了不同的相互作用力。此外,与碱基T相比,由碱基A修饰后表面所产生的横向力较大。
[Abstract]:The third generation gene sequencer based on nano-pore and related key technologies are of strategic significance for protecting our own gene resources. In order to realize this kind of gene sequencing technology, the main problems are as follows: first, the DNA molecule passes through the hole too fast, because of the passing through speed too fast, it is difficult to identify the base through the pore by testing the characteristic of the passing hole current; Second, the interaction mechanism between the four bases and the biological nano-pore wall is not clear. Further studies show that the greater the interaction force between DNA bases and the nano-pore wall, the smaller the thermal movement of ions in the nano fluid. The noise signal is mainly derived from the thermal movement of ions, and increasing the interaction force between DNA base and nano-pore wall is helpful to improve the signal-to-noise ratio (SNR). Therefore, it is of great significance for the third generation gene sequencing to study the wall specificity of DNA base. In this paper, the structure of two bases of DNA is analyzed, and the mechanical properties of monocrystalline silicon are studied based on the mechanical properties. The monocrystalline silicon is used as the substrate material to realize the assembly of DNA base biomolecules, and the modification mechanism is studied systematically. The influence factors of the fixed rate and the mechanical behavior of the modified surface under limited conditions. The characteristic peaks of adenine A and thymine T are different from those of other bases. The results of contact angle measurement showed that the time of complete silanization of silicon substrate was about 30min, and the complete molecular membrane was formed in the first time during the 20min reaction. The active amino group of DNA base chain reacts with the aldehyde group on the surface of silicon substrate and is immobilized on the silicon substrate. The results of fluorescence test showed that the concentration of silanization reagent had the greatest influence on the intensity of fluorescence background and the time of silanization was the least. The fixation rates of base A and T increased linearly with the increase of time when the concentration of silanized and aldehydized reagents was low, and the immobilization rates of base A and T showed maximum values when the concentration of reagents was higher. When the pH of the buffer solution of the probe is weak basic, the base fixation rate is larger, the probe sample concentration is 50 渭 mol/L, and the fixed rate of base A is higher than that of base T under the same condition. The results of nanomechanical study of monocrystalline silicon show that the elastic recovery rate of monocrystalline silicon increases with the increase of the half cone angle at the tip of the head for a given maximum loading force, and the elastic recovery is basically constant under the same experimental conditions. Compared with the (100) crystal face, the single crystal silicon (111) crystal mask has smaller hardness and elastic modulus, and with the increase of the maximum loading force, the material around the indentation of single crystal silicon will appear the phenomenon of stacking and surface bulging, and the elastic recovery of the indentation will increase. The range of plastic zone increases with the increase of loading force, and there is obvious size effect. The results of the mechanical behavior of the modified surface show that the normal force between the probe and the surface of the silicon wafer is less affected by the surface chemical morphology for the gap above 10nm in the atmospheric environment, and the gap below the 7nm is less affected by the normal force on the surface of the wafer. The interaction force between the surface and the probe was obviously decreased after the modification of the base, and the force between the probe and the base A and T was greatly affected by the loading rate. With the increase of the normal force, the transverse force between the probe and the silicon substrate increases, and the friction coefficient decreases gradually, and there are different interaction forces between the probe and the silicon wafer surface under different modification conditions. In addition, compared with base T, the surface modified by base A produces larger transverse force.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN304.12
本文编号：2253701
[Abstract]:The third generation gene sequencer based on nano-pore and related key technologies are of strategic significance for protecting our own gene resources. In order to realize this kind of gene sequencing technology, the main problems are as follows: first, the DNA molecule passes through the hole too fast, because of the passing through speed too fast, it is difficult to identify the base through the pore by testing the characteristic of the passing hole current; Second, the interaction mechanism between the four bases and the biological nano-pore wall is not clear. Further studies show that the greater the interaction force between DNA bases and the nano-pore wall, the smaller the thermal movement of ions in the nano fluid. The noise signal is mainly derived from the thermal movement of ions, and increasing the interaction force between DNA base and nano-pore wall is helpful to improve the signal-to-noise ratio (SNR). Therefore, it is of great significance for the third generation gene sequencing to study the wall specificity of DNA base. In this paper, the structure of two bases of DNA is analyzed, and the mechanical properties of monocrystalline silicon are studied based on the mechanical properties. The monocrystalline silicon is used as the substrate material to realize the assembly of DNA base biomolecules, and the modification mechanism is studied systematically. The influence factors of the fixed rate and the mechanical behavior of the modified surface under limited conditions. The characteristic peaks of adenine A and thymine T are different from those of other bases. The results of contact angle measurement showed that the time of complete silanization of silicon substrate was about 30min, and the complete molecular membrane was formed in the first time during the 20min reaction. The active amino group of DNA base chain reacts with the aldehyde group on the surface of silicon substrate and is immobilized on the silicon substrate. The results of fluorescence test showed that the concentration of silanization reagent had the greatest influence on the intensity of fluorescence background and the time of silanization was the least. The fixation rates of base A and T increased linearly with the increase of time when the concentration of silanized and aldehydized reagents was low, and the immobilization rates of base A and T showed maximum values when the concentration of reagents was higher. When the pH of the buffer solution of the probe is weak basic, the base fixation rate is larger, the probe sample concentration is 50 渭 mol/L, and the fixed rate of base A is higher than that of base T under the same condition. The results of nanomechanical study of monocrystalline silicon show that the elastic recovery rate of monocrystalline silicon increases with the increase of the half cone angle at the tip of the head for a given maximum loading force, and the elastic recovery is basically constant under the same experimental conditions. Compared with the (100) crystal face, the single crystal silicon (111) crystal mask has smaller hardness and elastic modulus, and with the increase of the maximum loading force, the material around the indentation of single crystal silicon will appear the phenomenon of stacking and surface bulging, and the elastic recovery of the indentation will increase. The range of plastic zone increases with the increase of loading force, and there is obvious size effect. The results of the mechanical behavior of the modified surface show that the normal force between the probe and the surface of the silicon wafer is less affected by the surface chemical morphology for the gap above 10nm in the atmospheric environment, and the gap below the 7nm is less affected by the normal force on the surface of the wafer. The interaction force between the surface and the probe was obviously decreased after the modification of the base, and the force between the probe and the base A and T was greatly affected by the loading rate. With the increase of the normal force, the transverse force between the probe and the silicon substrate increases, and the friction coefficient decreases gradually, and there are different interaction forces between the probe and the silicon wafer surface under different modification conditions. In addition, compared with base T, the surface modified by base A produces larger transverse force.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN304.12
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