Visualizing single-molecule diffusion in mesoporous materials
Visualizing single-molecule diffusion in mesoporous materials
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DOI：
10.1038/nature06398
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发表时间：
2007-11-29
期刊：
影响因子：
64.8
通讯作者：
Bein, Thomas
中科院分区：
文献类型：
--
作者：
Zuerner, Andreas;Kirstein, Johanna;Bein, Thomas
通过表面活性剂和框架构建块的协同自组装形成的周期性介孔材料可以具有多种结构（1-3），其广泛可调的性质使其具有许多应用的吸引力（4-7）。由于孔隙系统中的分子运动是多孔材料最重要和最具决定性的特征(8)，因此了解这种行为作为局部结构的函数是很有意义的。一般来说，单个荧光染料分子可以用作分子信标，用于探索这些多孔宿主的结构和内部动力学（9-13），单分子荧光技术提供了从生物学（14,15）到多相催化（16）等各种过程动力学的详细见解。然而，光学显微镜方法不能直接成像容纳扩散分子的宿主系统的介孔结构，而透射电子显微镜提供了多孔结构的详细图像（17），但没有动态信息。因此，不可能“看到”分子如何在真正的纳米级孔结构中扩散。在这里，我们提出了电子显微镜测绘和光学单分子跟踪实验的结合，以揭示单个发光染料分子如何穿过介孔通道系统的线性或强弯曲部分。在我们的方法中，我们直接将透射电子显微镜检测到的多孔结构与光学显微镜检测到的单分子扩散动力学联系起来。这为理解主人和客人之间的互动开辟了新的途径。
Periodic mesoporous materials formed through the cooperative self-assembly of surfactants and framework building blocks can assume a variety of structures(1-3), and their widely tuneable properties make them attractive hosts for numerous applications(4-7). Because the molecular movement in the pore system is the most important and defining characteristic of porous materials(8), it is of interest to learn about this behaviour as a function of local structure. Generally, individual fluorescent dye molecules can be used as molecular beacons with which to explore the structure of-and the dynamics within-these porous hosts(9-13), and single-molecule fluorescence techniques provide detailed insights into the dynamics of various processes, ranging from biology(14,15) to heterogeneous catalysis(16). However, optical microscopy methods cannot directly image the mesoporous structure of the host system accommodating the diffusing molecules, whereas transmission electron microscopy provides detailed images of the porous structure(17), but no dynamic information. It has therefore not been possible to 'see' how molecules diffuse in a real nanoscale pore structure. Here we present a combination of electron microscopic mapping and optical single-molecule tracking experiments to reveal how a single luminescent dye molecule travels through linear or strongly curved sections of a mesoporous channel system. In our approach we directly correlate porous structures detected by transmission electron microscopy with the diffusion dynamics of single molecules detected by optical microscopy. This opens up new ways of understanding the interactions of host and guest.