仿生DNA软表面纳米通道内受限流体电动传输的分子机理及界面特性研究

Transport and control of the confined fluid in biomimetic nanochannels with soft surfaces have received much attention and become increasingly important in nanofluidics. There are many applications in novel transport systems of microfluidics and nanofluidics, and they are of considerable importance in implementing the specific analysis and control functions at nanoscale. Compared to nanochannels with solid surfaces, it is difficult to understand the transport mechanism of the fluid confined within the biomimetic nanochannel with soft surfaces due to complicated properties of soft interface. Especially for soft surfaces consisting of biological macromolecules, such as DNA or proteins, their biological functions further increase the difficulty in theoretical investigations. In most cases, we must consider the molecular details of the interface to give successful prediction of the behavior of fluid transport. In the project, we use molecular simulations to investigate the transport mechanism of the fluid in the biomimetic nanochannels with soft DNA surfaces and their interface characteristics. Moreover, based on classical density functional theory of complex fluids we develop the transport theory of the fluid and the dynamics theory of the interface in the nanochannels with soft DNA surfaces. Further, we verify the correctness of the theory via molecular simulations and amend theoretical flaws to provide the theoretical basis at the molecular level for the improvement, design and fabrication of the biomimetic nanochannels with soft surfaces.

仿生软表面纳米通道内受限流体的传输及控制是纳流体动力学的前沿课题。在新型微纳流体控制系统上有着重要的应用前景，对实现纳米尺度下特定的分析及控制功能有着重要的意义。与固体表面纳米通道相比，仿生软表面纳米通道由于复杂的界面特性，使得我们很难通过经典的连续介质理论来理解其内部受限流体的传输机制。特别当软表面由生物大分子构成时，例如DNA和蛋白质，其特定的生物功能性将进一步增加理论研究的困难度。在大多数情况下必须考虑界面内分子的细节结构才能对纳米通道内流体的传输行为做出合理的预测。本课题针对这些问题，将通过分子模拟来研究仿生DNA软表面管道内流体的电动传输机理及界面特性。并基于复杂流体的经典密度泛函理论建立仿生DNA软表面通道内流体的电动传输理论及界面动力学理论。借助分子模拟的结果来验证理论的正确性，修正理论上存在的缺陷，进一步为仿生软表面纳米通道的改进、设计及制造提供分子水平上的理论依据。

仿生DNA软表面纳米通道具有良好的生物相容性、适应性及表面功能性，可以更好地模拟生物离子通道的功能。它们为新兴的单分子纳米孔传感器、下一代DNA 测序仪器、分子阀及离子整流设备等提供了可选择的解决方案。本项目可分为三个阶段：在第一阶段，建立了单链DNA的原子模型及粗粒化模型，研究了单个DNA链在受限空间中的构象及动力学，揭示了DNA分子在进入受限空间的过程中离子的聚集及释放行为；在第二阶段，基于第一阶段建立的DNA分子模型构建了DNA软表面纳米通道的模型，系统地研究了通道内流体的电动传输行为及其界面特性，定量分析了表面电荷分布、DNA分子表面粗糙度及离子特异性对流体传输性质的影响，为相关的实验提供了分子水平上的解释；在第三阶段，提出了纳米通道中流体电动传输的分子理论，通过这些理论研究了不同纳米通道中流体的流动特性，发现了在带电表面的疏水管道中存在反常电动传输现象，预测了基于粗粒化模型的DNA纳米通道中界面流体的结构及离子分布。