The Base Modification Of Single Si And Its Nano-Mechanical Behavior

Nanopore based third-generation gene sequencing instrument and related key technologies is of strategic significance for the protection of genetic resources of China. To realize such gene sequencing technology, currently the main problems exist are as following. The speed control of DNA molecule through the nanopore, biological molecules in the fluid environment of salt solution has not been established yet. An effectively control of the speed of DNA has not been realized yet. The present speed is too fast. The interaction mechanism of four bases and nanopore wall is not clear, leading to difficulty in biological information extraction and identification. Further studies showed that the larger the interaction of DNA bases and nanopore walls, the smaller the thermal motion of ions in the nanofluidic. While the noise signal mainly comes from the thermal motion of ions. Therefore, increasing the interaction force between the DNA base and the nano pore wall is helpful to improve the signal to noise ratio. So it is significant to study the interaction mechanism of four bases and nanopore wall for the third-generation gene sequencing.In this paper, the structure of two kinds of DNA bases was analyzed, and studied the nanomechanical properties of single crystal silicon from the mechanical properties. With single crystal silicon as the base material, the biomolecule of DNA bases were successfully assembled. At the same time, the modification mechanism, the influence factors of the fixed rate and the mechanical behavior of the modified surface under the limited conditions were systematic studied.Characterization test results showed that adenine and thymine molecules had characteristic peaks bases which were different from other molecules. The contact angle measurements display that completely silanized time of silicon substrate was about 30 min and the complete molecular membrane of aldehyde group was first formed at 20 min and growing layer by layer with the time. The DNA base chains were fixed on the silicon substrate since the active amino groups of the DNA base chain reacted with aldehyde groups.The results of orthogonal experiments indicates that in the four factors affecting the intensity of the fluorescence background, the concentration of the silane reagent had the greatest influence, and the time of the silane has the least. When the concentration of aldehyde reagent concentration and silylation reagent is low, the fixed rate of the base A and the base T showed a linear increase with time. When the reagent concentration is large, the fixed rate of base A and the base T appeared to a great value. When the pH of buffer solution showed weak base, the base fixed rate is larger. When the probe spotting concentration was 50μmol/L, the fixed rate of the base was higher. Under the same condition, the rate of base A fixation was higher than that of base T.For the established maximum loading, as the indenter tip half cone angle increases, silicon elastic recovery rate increased, but the amount of spring back substantially constant. In the same experimental conditions, compared to the(100) crystal surface, the hardness and elastic modulus of silicon(111) crystal surface had a smaller value. With the increase of the maximum loading force, the material around the single crystal silicon indentation would appear the phenomenon of accumulation and surface uplift, the elastic recovery of the indentation increased, and the range of plastic zone increased with the loading force. There was an obvious size effect. In the atmospheric environment, for the clearance of more than 10 nm, the normal force acting between probe and silicon surface is less affected by the surface chemical morphology. For the clearance of less than 7nm, the force between the modified surface and probe was significantly reduced, and the interaction between the probe and the base A and the base T were greatly influenced by the loading rate. With the increase of normal force, the lateral force between the probe and the silicon substrate increased, and the friction coefficient decreased gradually. Different interaction forces are generated on the silicon surface under different conditions. In addition, compared with the base T, the lateral force modified by the base A is larger.