Ernst Matthias, John Thomas, Guenther Marco, Wagner Christian, Schaefer Ulrich F, Lehr Claus-Michael
Faculty of Engineering, Department of Applied Mathematics, University of Applied Sciences, Saarbrücken, Germany.
Department of Experimental Physics, Saarland University, Saarbrücken, Germany.
Biophys J. 2017 Jan 10;112(1):172-179. doi: 10.1016/j.bpj.2016.11.900.
In this study we have applied a model to explain the reported subdiffusion of particles in mucus, based on the measured mean squared displacements (MSD). The model considers Brownian diffusion of particles in a confined geometry, made from permeable membranes. The applied model predicts a normal diffusive behavior at very short and long time lags, as observed in several experiments. In between these timescales, we find that the "subdiffusive" regime is only a transient effect, MSD∝τ,α<1. The only parameters in the model are the diffusion-coefficients at the limits of very short and long times, and the distance between the permeable membranes L. Our numerical results are in agreement with published experimental data for realistic assumptions of these parameters. Finally, we show that only particles with a diameter less than 40 nm are able to pass through a mucus layer by passive Brownian motion.
在本研究中，我们基于测量的平均平方位移（MSD）应用了一个模型来解释所报道的颗粒在黏液中的亚扩散现象。该模型考虑了颗粒在由可渗透膜构成的受限几何结构中的布朗扩散。所应用的模型预测在非常短和非常长的时间滞后时会出现正常的扩散行为，这在多个实验中都有观察到。在这些时间尺度之间，我们发现“亚扩散”状态只是一种瞬态效应，MSD∝τ，α<1。该模型中仅有的参数是非常短和非常长时间极限下的扩散系数，以及可渗透膜之间的距离L。我们的数值结果与针对这些参数的实际假设所发表的实验数据一致。最后，我们表明只有直径小于40纳米的颗粒能够通过被动布朗运动穿过黏液层。
