Cellular Informatics Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
J Control Release. 2012 Nov 10;163(3):315-21. doi: 10.1016/j.jconrel.2012.07.036. Epub 2012 Aug 16.
For quantitative analysis of nanoparticle diffusions and submicro-environments in living cells, use of newly synthesized silica-based fluorescent nanoparticle (Si-FNP) as a standard nanoprobe is successfully demonstrated. The appropriate characteristics of a standard probe were fully analyzed in vitro by single molecule detection, transmission electron microscopy, and dynamic light scattering. Using fluorescence correlation analysis in single living cells, we quantitatively compared the diffusional properties of the standard Si-FNP with a diameter of 50 nm, peptide coated Si-FNP, streptavidin coated Qdot, and GFP molecule which have different sizes and surface properties. The result demonstrates that the standard Si-FNP without coat is minimally trapped in the vesicles in the process of cellular endocytosis. Interestingly, a large proportion of Si-FNP introduced into the cells by electroporation diffuses freely in the cells during a cell cycle suggesting free diffusing NPs are hardly trapped in the vesicles. The simple but highly sensitive method will provide insight into strategies to understanding the hydrodynamic process of nanoparticle delivery into living cells as well as the cellular microenvironment in the view of submicro-size.
为了定量分析活细胞内纳米颗粒的扩散及其亚微观环境，成功地将新合成的基于硅的荧光纳米颗粒（Si-FNP）用作标准纳米探针。通过单分子检测、透射电子显微镜和动态光散射，在体外充分分析了标准探针的适当特性。在单个活细胞中使用荧光相关分析，我们定量比较了直径为 50nm 的标准 Si-FNP、肽涂覆的 Si-FNP、链霉亲和素涂覆的 Qdot 和 GFP 分子的扩散性质，这些分子具有不同的大小和表面性质。结果表明，在细胞内吞过程中，未涂覆的标准 Si-FNP 最小程度地被囊泡捕获。有趣的是，通过电穿孔引入细胞的大量 Si-FNP 在细胞周期中自由扩散，这表明自由扩散的 NPs 几乎不会被囊泡捕获。这种简单但高度敏感的方法将深入了解纳米颗粒递送至活细胞以及从亚微观角度看待细胞微环境的动力学过程的策略。
