Crowding-induced anisotropic transport modulates reaction kinetics in nanoscale porous media.
Crowding-induced anisotropic transport modulates reaction kinetics in nanoscale porous media.
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拥挤引起的各向异性传输调节纳米级多孔介质中的反应动力学。
DOI：
10.1021/jp9025865
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Grima R
中科院分区：
文献类型：
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作者：
Grima R
我们量化的出现持久的各向异性的球形示踪剂颗粒的扩散通过纳米多孔介质组成的均匀分布的纯对称拥挤的颗粒。我们专注于内部的生物细胞作为这样的介质的一个例子，并发现扩散是高度定向的距离可比的一些细胞器的大小。我们使用的几何过程，避免了标准的取向平均量化扩散路径的各向异性，并表明，点源分布主要是长椭球形的局部体积排斥的结果。这种几何对称性破缺强烈地使扩散限制反应的动力学速率的分布向小的值倾斜，导致这样的结果，即对于短到中间的时间，在非均质介质的集合中测量的速率的几乎80%小于在类似排除体积分数的理想均质介质中的预期速率。这种拥挤诱导的调制可能会影响我们的理解和测量扩散控制的细胞内反应动力学和实验纳米技术的应用，如基于纳米粒子的生物成像和药物输送，其中扩散起着重要的作用。
We quantify the emergence of persistent anisotropy in the diffusion of spherical tracer particles through a nanoscale porous medium composed of a uniform distribution of purely symmetric crowding particles. We focus on the interior of a biological cell as an example of such a medium and find that diffusion is highly directional for distances comparable to the size of some organelles. We use a geometrical procedure that avoids the standard orientational averaging to quantify the anisotropy of diffusive paths and show that the point source distributions are predominantly of prolate ellipsoidal shape as a result of local volume exclusion. This geometrical symmetry breaking strongly skews the distribution of kinetic rates of diffusion-limited reactions toward small values, leading to the result that, for short to intermediate times, almost 80% of the rates measured in an ensemble of heterogeneous media are smaller than the expected rate in an ideal homogeneous medium of similar excluded volume fraction. This crowding-induced modulation may have implications for our understanding and measurement of diffusion-controlled intracellular reaction kinetics and for experimental nanotechnology applications, such as nanoparticle-based bioimaging and drug delivery, where diffusion plays an important role.