Cosentino Carlo, Amato Francesco, Walczak Robbie, Boiarski Anthony, Ferrari Mauro
Department of Experimental and Clinical Medicine, Università degli Studi Magna Graecia di Catanzaro, via T. Campanella 115, 88100 Catanzaro, Italy.
J Phys Chem B. 2005 Apr 21;109(15):7358-64. doi: 10.1021/jp045478u.
The molecular diffusion dynamics in unconstrained cases has been studied thoroughly during the last two centuries, leading to the well-known Fick's diffusion laws and Stokes-Einstein equation. More recently, a new impulse to the study of this topic has been provided by the necessity of understanding the behavior of solute particles in the presence of environmental constraints of size comparable to the molecular dimensions. In this work, we investigate the diffusion kinetics of biomolecules, such as bovine serum albumin, interferon, and lysozyme, through microfabricated silicon membranes, having pores of nanometric size in only one dimension, in the range from few to tens of nanometers (the other dimensions are in the mum range). Experimental results show that the diffusion profiles, in some cases, deviate substantially from those predicted by Fick's laws. In light of these results, a new diffusion mathematical model is proposed, which can reasonably explain the phenomenon and, at the same time, recovers the classical diffusion laws in the unconstrained case. Moreover, a physical description, derived from van der Waals equation of state, is presented, and it is compared with the results obtained by the mathematical model.
在过去的两个世纪里，人们对无约束情况下的分子扩散动力学进行了深入研究，得出了著名的菲克扩散定律和斯托克斯 - 爱因斯坦方程。最近，由于需要了解溶质颗粒在存在与分子尺寸相当的环境约束时的行为，这一主题的研究有了新的推动力。在这项工作中，我们研究了生物分子（如牛血清白蛋白、干扰素和溶菌酶）通过微加工硅膜的扩散动力学，该硅膜仅在一个维度上具有纳米尺寸的孔，孔径范围从几纳米到几十纳米（其他维度在毫米范围内）。实验结果表明，在某些情况下，扩散曲线与菲克定律预测的曲线有很大偏差。鉴于这些结果，提出了一种新的扩散数学模型，该模型可以合理地解释这一现象，同时在无约束情况下恢复经典扩散定律。此外，还给出了基于范德华状态方程的物理描述，并将其与数学模型得到的结果进行了比较。
