細胞機能を可視化する新奇な超分子ナノ材料の光創製

我们这项计划的目的是开发一种新型的低毒、化学稳定和高发光的纳米颗粒，用于单分子生物传感和成像，利用光作为一种资源丰富的工具。在本项目中，我们制备了两种新型的荧光纳米材料，它们是富勒烯壳层的CdSe-ZnS量子点和金量子簇(AU25)。在这里，富勒烯壳层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中的金离子而制备的。首先，通过多步热化学路线合成了富勒烯硫醇分子。随后，通过S-S键将富勒烯硫醇连接到硫化锌表面，在量子点表面制备了富勒烯单层。最后，富勒烯硫醇单层保护的量子点被浸泡在过量的富勒烯硫醇中并光活化。我们发现在量子点表面形成了稳定而厚实的富勒烯壳层，这是由于2+2光环加成反应的结果。进一步，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QD最有趣的特性是它能够显示被抑制的眨眼。虽然富勒烯壳量子点表现出适合单分子生物成像和太阳能收集的闪烁抑制，但AU25的生物偶联物有效地进入人体细胞，使我们能够获得活细胞的近红外荧光图像。这两种类型的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美国化学学会纳米6,1601-1608,2012年。

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.