复杂流体中纳米颗粒的流动介导扩散研究

Nanoparticle diffusion in complex physiological media plays an important role in the processes of life evolution, information transmission and drug delivery. The complexity of the physiological media lies mainly on the porous structure and the flowing environment. As modeled porous liquids, polymer solutions are often used to investigate the diffusion mechanism of nanoparticles. Most existing studies in polymer solutions have been conducted in thermodynamic equilibrium, thus the resultant diffusion mechanism does not apply to the flowing physiological media. In this project, the flowing environment of polymer solutions will be constructed using the microfluidic technology, and the motions of the immersed nanoparticles are then measured by the particle tracking technology. The characteristics of nanoparticle motions are then studied based on the mean square displacement, displacement probability distribution, non-Gaussianity, displacement autocorrelation coefficient, and ergodicity breaking parameter. The effects of rheological properties of polymer solution, flow channel structure, and particle size on the motions of nanoparticles are analyzed, and the microscopic motion mechanism of nanoparticles is then explored. The macroscopic description model of the flow-mediated diffusion is finally established by the combination of fractional derivative diffusion equation and experimental results. This project can provide some theoretical references for the interpretation of potential molecular mechanisms under cell functions, the regulation and evaluation of nanomedicine transportation, and so on.

复杂生理介质中的纳米颗粒扩散在生命演化、信息传递、药物输运等过程中具有重要意义。生理介质的复杂性主要在于多孔结构和流动特性。作为模型化的多孔介质流体，高分子溶液常被用以考察纳米颗粒的扩散机制。已有研究大都在热力学平衡态的高分子溶液中进行，得出的扩散机制并不适用于流动的生理介质。本项目将利用微流控技术构建高分子溶液流动环境，采用粒子追踪技术测量其中纳米颗粒的运动；基于均方位移、位移概率分布、非高斯系数、位移自相关系数以及遍历破坏参数等表征量，考察纳米颗粒的运动特性；分析高分子溶液流变特性、流道结构、颗粒尺寸等方面因素对纳米颗粒运动的影响规律，探索纳米颗粒的微观运动机制；结合分数阶导数扩散方程和实验结果，建立流动介导扩散的宏观描述模型。该项目研究可为细胞功能潜在分子机制的解读、纳米药物的输运调控及评估等提供一定的理论参考。

复杂生理介质中的纳米颗粒扩散在生命演化、信息传递、药物输运等过程中具有重要意义。生理介质的复杂性主要在于多孔结构和流动特性。作为模型化的多孔介质流体，高分子溶液常被用以考察纳米颗粒的扩散机制。已有研究大都在热力学平衡态的高分子溶液中进行，得出的扩散机制并不适用于流动的生理介质。本项目利用微流控技术设计和构建了高分子溶液简单流动环境、温度调控环境及活细胞内部环境三种复杂流体流动环境；采用粒子追踪技术测量了所构建环境中纳米颗粒的运动，并基于均方位移、位移概率分布、非高斯系数、位移自相关系数以及遍历破坏参数等统计量进行纳米颗粒运动特性表征；对比热力学平衡态下高分子溶液中的纳米颗粒运动特性，分析高分子网络结构，颗粒尺寸，细胞骨架等因素对纳米颗粒运动的影响，阐明了高分子溶液中纳米颗粒的激活跳跃扩散、流动对扩散影响规律以及细胞骨架对纳米颗粒扩散的影响机制。研究结果不仅可为复杂流体环境中纳米颗粒扩散研究提供有效平台，还可为细胞功能潜在分子机制的解读、纳米药物的输运调控及评估等提供一定的理论参考。