細胞機能を可視化する新奇な超分子ナノ材料の光創製

我们的目标是开发一种新型的低毒性，化学稳定，高发光纳米粒子的单分子生物传感和成像使用光作为一种资源丰富的工具。本项目制备了两种新型的荧光纳米材料，即富勒烯壳层的CdSe-ZnS量子点和金量子簇（Au 25）。在这里，富勒烯壳量子点是通过光化学方法制备的;而量子簇是通过碱性还原牛血清白蛋白口袋内的金离子制备的。首先，采用多步热化学法合成了富勒烯硫醇分子。随后，通过将富勒烯硫醇通过S-S键连接到ZnS表面，在QD表面上制备富勒烯单层。最后，将富勒烯硫醇单层保护的QD浸入过量的富勒烯硫醇中并光活化。我们发现量子点表面形成了稳定且厚的富勒烯壳层，这是由于2+2的光环加成反应。此外，我们在系综和单分子水平上表征了它们的光致发光性质。富勒烯壳量子点最有趣的特性是它能够抑制闪烁。虽然富勒烯壳量子点显示出适合于单分子生物成像和太阳能收集的闪烁抑制; Au 25的生物缀合物有效地进入人体细胞，使我们能够获得活细胞的NIR荧光图像。这两种荧光纳米材料使我们能够与日本的四个研究小组建立合作关系。这项研究的一部分发表在ACS Nano 6，1601-1608，2012。

Our aim of this proposal is to develop a novel low-toxic, chemically stable, and highly-luminescent nanoparticles for single-molecule bio-sensing and -imaging using light as a resourceful tool. In this project, two types of novel fluorescent nanomaterials are prepared, which are fullerene-shelled CdSe-ZnS quantum dots and gold quantum clusters (Au25). Here, fullerene-shelled quantum dots are prepared by a photochemical method ; whereas, the quantum clusters are prepared by the alkaline reduction of gold ions within the pockets of bovine serum albumin. At first, a fullerene thiol molecule was synthesized by multi-step thermal chemical route. Subsequently, a monolayer of fullerene is prepared on the surface of QD by the tethering of the fullerene thiol to the ZnS surface through the S-S bonding. Finally, the fullerene thiol monolayer-protected QDs were immersed in excess fullerene thiol and photoactivated. We found the formation stable and thick fullerene shells on the surface of QDs, which is due to the 2+2 photocycloaddition reaction. Further, we characterized their photoluminescence properties at ensemble and single-molecule levels. The most interesting property of the fullerene-shelled QD is its ability to show suppressed blinking. While fullerene-shelled quantum dots show blinking suppression that is suitable for single-molecule bioimaging and solar energy harvesting ; bioconjugates of Au25 efficiently entered human cells and enabled us for obtaining NIR fluorescence images of live cells. The two types of fluorescent nanomaterials enabled us for establishing collaborations with four research groups in Japan. A part of this research is published in ACS Nano 6, 1601-1608, 2012.