Intracellular diffusion is critical for molecule translocation in cytoplasm and mediates many important cellular processes. Meanwhile, the diffusion dynamics is affected by the heterogeneous cytoplasm. Previous studies on intracellular diffusion are mainly based on two-dimensional (2D) measurements under the assumption that the three-dimensional (3D) diffusion is isotropic. However, the real behaviors of 3D diffusion of molecules in cytoplasm are still unclear. Here, we have built a 3D single-particle tracking (SPT) microscopy and studied the 3D diffusion of quantum dots (QDs) in adherent A549 cells. Notably, we found that the intracellular diffusion of QDs is quasi-2D, with the axial motion being severely confined. Further investigations demonstrated that disrupting the cytoskeleton component or endoplasmic reticulum (ER) does not alter the quasi-2D diffusion pattern, although ER reduces the diffusion rates and slightly relieves the constraint in the axial diffusion. The prefer...

中文翻译：

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三维单量子点跟踪揭示了粘附细胞中的准二维扩散

细胞内扩散对于分子在细胞质中的转运至关重要，并介导许多重要的细胞过程。同时，扩散动力学受异质性细胞质的影响。先前关于细胞内扩散的研究主要基于二维（2D）测量，并假设三维（3D）扩散是各向同性的。但是，尚不清楚分子在细胞质中进行3D扩散的真实行为。在这里，我们建立了3D单粒子跟踪（SPT）显微镜，并研究了粘附A549细胞中量子点（QD）的3D扩散。值得注意的是，我们发现量子点的细胞内扩散是准2D的，其轴向运动受到严格限制。进一步的研究表明，破坏细胞骨架成分或内质网（ER）不会改变准2D扩散模式，尽管ER降低了扩散速率并稍微减轻了轴向扩散的限制。首选...