【摘要】：在微納芯片和生物傳感器的實(shí)際應(yīng)用中,利用微流體通道電場力驅(qū)動操作并分析單個生物大分子的特性,可以準(zhǔn)確、靈活地實(shí)現(xiàn)對單分子的控制。本文基于三電極體系,系統(tǒng)地研究了電場力驅(qū)動下DNA及PS納米小球穿越微納通道(內(nèi)徑10 μm,5 μm,500 nm,200nm,100 nm)時的特征電流信號。研究發(fā)現(xiàn)微納通道尺寸、溶液pH以及緩沖液濃度都會影響微納流的電流響應(yīng)信號,并且出現(xiàn)臨界電壓的現(xiàn)象。這些對于微流控技術(shù)與設(shè)備的改進(jìn)以及信噪比的提高有著重要的意義。本文的主要內(nèi)容及結(jié)論包含以下幾個方面:(1)實(shí)驗(yàn)發(fā)現(xiàn),不同尺寸通道均有相同的電流現(xiàn)象,即:初始電流響應(yīng)有瞬態(tài)上升值與瞬態(tài)下降值,而后隨時間改變最終趨于穩(wěn)定。理論分析認(rèn)為是電極極化以及雙電層影響下的電滲流共同作用的結(jié)果。(2)研究了 DNA分子/PS納米小球溶液在微/納通道的電流信號。當(dāng)通道內(nèi)只加入純的TBE溶液時,電導(dǎo)并不是隨通道直徑減小而單調(diào)遞減,而是在亞微米尺度隨通道直徑的減小而增加。實(shí)驗(yàn)觀察到200 nm通道在外加電壓20 mV時的電導(dǎo)瞬態(tài)下降現(xiàn)象。當(dāng)DNA分子或PS納米粒子加入時,通道尺寸效應(yīng)引起的電導(dǎo)規(guī)律也不同。(3)通過對加入λ-DNA和羧化PS納米小球在不同尺寸的通道、不同偏置電壓、緩沖液濃度、pH等的電流響應(yīng)進(jìn)行研究,利用表面電荷、電滲流及雙電層的有關(guān)理論分析了上述條件對電流信號影響的機(jī)理:發(fā)現(xiàn)臨界電壓隨著緩沖液pH、通道尺寸的增大而減小,隨緩沖液濃度的增加而增大。pH對信噪比的影響:pH越大,信噪比越低。(4)在100nm通道中,隨著pH的增加,穩(wěn)定電流I也隨之增大。臨界電壓隨著pH的增加而減小;隨著緩沖液濃度的增加,臨界電壓反而越小。在外加電壓小于臨界電壓Uc時,隨著電壓增加,穩(wěn)定電流絕對值反而減小。通過對電流響應(yīng)信號與臨界電壓的分析,進(jìn)而探討DNA、PS納米小球在通道中的運(yùn)動特性,有助于研制具有特殊功能的微/納米通道流體傳感器和生物芯片。
[Abstract]:In the practical application of micronano chip and biosensor, the control of single molecule can be realized accurately and flexibly by using the microfluid channel electric force driving operation and analyzing the characteristics of a single biological macromolecule. Based on the three-electrode system, the characteristic current signals of DNA and PS nanospheres traversing micro-nano channels (10 渭 m ~ 5 渭 m ~ (500 nm,200nm,100 nm) in diameter) driven by electric field force are studied systematically in this paper. It is found that the size of the microchannel, the solution pH and the buffer concentration all affect the current response signal of the micronano flow and the phenomenon of critical voltage appears. These are of great significance for the improvement of microfluidic technology and equipment and the improvement of signal-to-noise ratio (SNR). The main contents and conclusions of this paper include the following aspects: (1) the experimental results show that there are the same current phenomena in the channels of different sizes, that is, the initial current response has transient upward appreciation and transient decline. Then it changes over time and eventually stabilizes. Theoretical analysis shows that this is the result of electrode polarization and electroosmotic interaction under the influence of double layer. (2) the current signal of DNA molecule / PS nanoparticles solution in microchannel / nanowires is studied. When only pure TBE solution is added into the channel, the conductance does not decrease monotonously with the decrease of channel diameter, but increases with the decrease of channel diameter at sub-micron scale. The transient decrease of conductance of 200 nm channel was observed at applied voltage of 20 mV. When the DNA molecule or PS nanoparticles were added, the channel size effect caused different conductance. (3) by adding 位-DNA and carboxylation PS nanoparticles in different size channels, different bias voltage, buffer concentration, The current response of pH et al is studied. The mechanism of the influence of the above conditions on the current signal is analyzed by using the theories of surface charge, electroosmotic flow and double layer. It is found that the critical voltage decreases with the increase of the buffer pH, channel size. The effect of pH on SNR increases with the increase of buffer concentration: the greater the pH, the lower the SNR. (4) in the 100nm channel, the stable current I increases with the increase of pH. The critical voltage decreases with the increase of pH and decreases with the increase of buffer concentration. When the applied voltage is less than the critical voltage Uc, the absolute value of the stable current decreases with the increase of the voltage. By analyzing the current response signal and critical voltage, the motion characteristics of DNA,PS nanoparticles in the channel are discussed, which is helpful to the development of micro / nano-channel fluid sensors and biochips with special functions.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;O441.1

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本文編號：2426585