State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Peoples Republic of China.
Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2019 Sep 13;123(11):118002. doi: 10.1103/PhysRevLett.123.118002.
Narrow escape from confinement through a nanochannel is the critical step of complex transport processes including size-exclusion-based separations, oil and gas extraction from the microporous subsurface environment, and ribonucleic acid translocation through nuclear pore complex channels. While narrow escape has been studied using theoretical and computational methods, experimental quantification is rare because of the difficulty in confining a particle into a microscopic space through a nanoscale hole. Here, we studied narrow escape in the context of continuous nanoparticle diffusion within the liquid-filled void space of an ordered porous material. Specifically, we quantified the spatial dependence of nanoparticle motion and the sojourn times of individual particles in the interconnected confined cavities of a liquid-filled inverse opal film. We found that nanoparticle motion was inhibited near cavity walls and cavity escape was slower than predicted by existing theories and random-walk simulations. A combined computational-experimental analysis indicated that translocation through a nanochannel is barrier controlled rather than diffusion controlled.
通过纳米通道的狭窄逃生是复杂传输过程的关键步骤，这些过程包括基于尺寸排阻的分离、从微孔地下环境中提取石油和天然气，以及核糖核酸通过核孔复合通道的转位。虽然已经使用理论和计算方法研究了狭窄逃生，但由于通过纳米级孔将颗粒限制在微观空间中非常困难，因此很少进行实验量化。在这里，我们在有序多孔材料的充满液体的空隙空间内连续纳米颗粒扩散的背景下研究了狭窄逃生。具体来说，我们量化了纳米颗粒在充满液体的反蛋白石膜相互连接的受限腔中的运动的空间依赖性以及单个颗粒的停留时间。我们发现，颗粒在腔壁附近的运动受到抑制，并且腔逃逸速度比现有理论和随机游走模拟预测的要慢。组合的计算实验分析表明，纳米通道的转位是由势垒控制而不是扩散控制。
