New fluorescence correlation spectroscopy enabling direct observation of spatiotemporal dependence of diffusion constants as an evidence of anomalous transport in extracellular matrices
New fluorescence correlation spectroscopy enabling direct observation of spatiotemporal dependence of diffusion constants as an evidence of anomalous transport in extracellular matrices
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DOI：
10.1529/biophysj.104.048009
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发表时间：
2005-05-01
影响因子：
3.4
通讯作者：
Riken, TO
中科院分区：
文献类型：
--
作者：
Masuda, A;Ushida, K;Riken, TO
荧光相关光谱（FCS）的潜力被扩展到能够直接观察非均匀介质中的异常亚扩散（ASD），特别是在许多生物系统中，如膜、细胞质和细胞外基质（ecm）中非常重要。由于ASD可以通过监测可观测扩散系数（D-obs）的时空依赖性来确认，因此使用电动可变光束扩展器在300-500 nm范围内连续改变FCS采样的有效共聚焦体积（V-eff）（采样体积）的大小。由于透明质酸（HA） 7-33 nm的网络结构（纳米结构）干扰了其内部的物质运输，因此发光溶质（Alexa 488）的Dobs发生了显著变化，对应于半轴上220-340 nm的V-eff变化，该方法被应用于透明质酸（HA）水溶液的分析。结果表明，即使在ECM中存在少量（约0.1 wt %） HA，也可能发生中度ASD。由于即使在没有自相关函数变形的系统中，D-obs随移动距离（均方位移）的变化也可以被识别，因此该技术在ASD表现出复杂的时间和空间依赖性的许多生物系统中具有很大的应用潜力。
The potential of fluorescence correlation spectroscopy (FCS) is extended to enable the direct observation of anomalous subdiffusion (ASD) in inhomogeneous media that are of great importance particularly in many biological systems, such as membranes, cytoplasm, and extracellular matrices (ECMs). Because ASD can be confirmed by monitoring the spatiotemporal dependence of observable diffusion coefficients (D-obs), the size of the effective confocal volume (V-eff) for FCS sampling ( sampling volume) was continuously changed on a scale of 300-500 nm using a motorized variable beam expander through which an illuminating laser beam passes. This new method, namely, sampling-volume-controlled (SVC)-FCS, was applied to the analysis of hyaluronan ( HA) aqueous solutions where the Dobs of light-emitting solute ( Alexa 488) markedly changed, corresponding to the change in V-eff (220-340 nm in the half-axis), because the network structure of HA of 7-33 nm (nanostructure) interferes with the material transport within it. The results indicate that moderate ASD may occur even in the presence of a small amount (similar to 0.1 wt %) of HA in ECM. Because the change in D-obs along with the traveling distance (the mean-square displacement) can be identified even in systems with no deformation of the autocorrelation function, this technique has a great potential for general applications to many biological systems in which ASD shows complex time and space dependences.