"Cloud" assemblies: quantum dots form electrostatically bound dynamic nebulae around large gold nanoparticles.
"Cloud" assemblies: quantum dots form electrostatically bound dynamic nebulae around large gold nanoparticles.
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DOI：
10.1039/c0cp00186d
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发表时间：
2010-09
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影响因子：
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通讯作者：
G. Lilly;Jaebeom Lee;N. Kotov
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文献类型：
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作者：
G. Lilly;Jaebeom Lee;N. Kotov
纳米颗粒的动态自组装结构可以利用主要的静电相互作用来制造。这种组装是由大的、带正电的金金属纳米颗粒组成的，周围环绕着由较小的带负电的CdSe/ZnS或CdTe量子点组成的静电束缚云。在低浓度时，它们在拓扑结构上类似于由聚合物链连接的双电层离子和电晕状组件。它们还可以比作太空中一些行星系统的拓扑排列。云组件的巨大优势是(1)与更刚性的共价结合组件相比，它们具有高度的动态性质，(2)制备简单，以及(3)在组件和所产生的光学性质方面具有出众的多功能性。虽然CdTe量子点表现出发射猝灭，但观察到了激子与等离子体之间的量子共振导致的光致发光增强。为了更仔细地评估它们的动态行为，收集了不同成分比例和介质离子强度的云团的发射数据。该系统的发射最多通过80个量子点：1个Au Np，这取决于组件的结构和光吸收条件。发光强度对离子强度的依赖关系与基于Gouy-Chapman理论的预测和高离子强度下的渗透压相矛盾，因为形成了更大的混沌胶体稳定集合体。由不同纳米级组件制成的“云”组件既可用于阐明纳米粒子相互作用的最基本方面，也可用于传感和生物学的实际目的。
Dynamic self-assembled structures of nanoparticles can be produced using predominantly electrostatic interactions. Such assemblies were made from large, positively charged Au metal nanoparticles surrounded by an electrostatically bound cloud of smaller, negatively charged CdSe/ZnS or CdTe quantum dots. At low concentrations they are topologically similar to double electric layers of ions and corona-like assemblies linked by polymer chains. They can also be compared to the topological arrangement of some planetary systems in space. The great advantages of the cloud assemblies are (1) their highly dynamic nature compared to more rigid covalently bound assemblies, (2) simplicity of preparation, and (3) exceptional versatility in components and resulting optical properties. Photoluminescence intensity enhancement originating from quantum resonance between excitons and plasmons was observed for CdSe/ZnS quantum dots, although CdTe dots displayed emission quenching. To evaluate more attentively their dynamic behavior, emission data were collected for the cloud-assemblies with different ratios of the components and ionic strengths of the media. The emission of the system passes through a maximum for 80 QDs ∶ 1 Au NP as determined by the structure of the assemblies and light absorption conditions. Ionic strength dependence of luminescence intensity contradicts the predictions based on the Gouy-Chapman theory and osmotic pressure at high ionic strengths due to formation of larger chaotic colloidally stable assemblies. "Cloud" assemblies made from different nanoscale components can be used both for elucidation of most fundamental aspects of nanoparticle interactions, as well as for practical purposes in sensing and biology.