Imaging Barriers to Diffusion by Pair Correlation Functions
Imaging Barriers to Diffusion by Pair Correlation Functions
复制标题
DOI：
10.1016/j.bpj.2009.04.048
复制
发表时间：
2009-07-22
影响因子：
3.4
通讯作者：
Gratton, Enrico
中科院分区：
文献类型：
--
作者：
Digman, Michelle A.;Gratton, Enrico
分子扩散和传输是物理、化学、生物化学和生物系统中的基本过程。然而，目前的方法来测量细胞和组织中的分子运输的基础上扰动的方法，如荧光恢复后光漂白是侵入性的，波动相关的方法是本地的，和单粒子跟踪需要观察孤立的粒子相对较长的时间。我们建议通过测量样品中一对位置的波动的时间互相关来检测分子输运。当两个点之间的距离超过点扩散函数的两倍时，相关性的最大值与分子从一个特定位置移动到另一个位置所需的平均时间成正比。我们演示的方法，通过模拟，使用珠在溶液中，并通过测量分子在细胞膜中的扩散。空间对互相关方法检测扩散的障碍和扩散的异质性，因为在扩散障碍的存在下，相关最大值的时间被延迟。这种非侵入性的，敏感的技术在大面积上跟踪相同的分子，从而产生分子流图。它不需要分离的分子，因此可以同时标记许多分子，并且在点扩散函数内。
Molecular diffusion and transport are fundamental processes in physical, chemical, biochemical, and biological systems. However, current approaches to measure molecular transport in cells and tissues based on perturbation methods such as fluorescence recovery after photobleaching are invasive, fluctuation correlation methods are local, and single-particle tracking requires the observation of isolated particles for relatively long periods of time. We propose to detect molecular transport by measuring the time cross-correlation of fluctuations at a pair of locations in the sample. When the points are farther apart than two times the size of the point spread function, the maximum of the correlation is proportional to the average time a molecule takes to move from a specific location to another. We demonstrate the method by simulations, using beads in solution, and by measuring the diffusion of molecules in cellular membranes. The spatial pair cross-correlation method detects barriers to diffusion and heterogeneity of diffusion because the time of the correlation maximum is delayed in the presence of diffusion barriers. This noninvasive, sensitive technique follows the same molecule over a large area, thereby producing a map of molecular flow. It does not require isolated molecules, and thus many molecules can be labeled at the same time and within the point spread function.