School of Food Science and Technology, State Key Lab of Food Science and Technology, Jiangnan University, Wuxi, JiangSu, 214122, People's Republic of China.
J Am Chem Soc. 2012 Jan 25;134(3):1699-709. doi: 10.1021/ja2088713. Epub 2012 Jan 13.
Multiple properties of plasmonic assemblies are determined by their geometrical organization. While high degree of complexity was achieved for plasmonic superstructures based on nanoparticles (NPs), little is known about the stable and structurally reproducible plasmonic assemblies made up from geometrically diverse plasmonic building blocks. Among other possibilities, they open the door for the preparation of regiospecific isomers of nanoscale assemblies significant both from a fundamental point of view and optical applications. Here, we present a synthetic method for complex assemblies from NPs and nanorods (NRs) based on selective modification of NRs with DNA oligomers. Three types of assemblies denoted as End, Side, and Satellite isomers that display distinct elements of regiospecificity were prepared with the yield exceeding 85%. Multiple experimental methods independently verify various structural features, uniformity, and stability of the prepared assemblies. The presence of interparticle gaps with finely controlled geometrical parameters and inherently small size comparable with those of cellular organelles fomented their study as intracellular probes. Against initial expectations, SERS intensity for End, Side, and Satellite isomers was found to be dependent primarily on the number of the NPs in the superstructures rationalized with the help of electrical field simulations. Incubation of the label-free NP-NR assemblies with HeLa cells indicated sufficient field enhancement to detect structural lipids of mitochondria and potentially small metabolites. This provided the first proof-of-concept data for the possibility of real-time probing of the local organelle environment in live cells. Further studies should include structural optimization of the assemblies for multitarget monitoring of metabolic activity and further increase in complexity for applications in transformative optics.
等离子体组装体的多种性质取决于其几何组织。虽然基于纳米粒子 (NPs) 的等离子体超结构已经实现了高度的复杂性，但对于由几何形状不同的等离子体构建块组成的稳定且结构可重复的等离子体组装体却知之甚少。除其他可能性外，它们为制备纳米级组装体的区域特异性异构体开辟了道路，这些异构体从基础和光学应用的角度来看都具有重要意义。在这里，我们提出了一种基于 DNA 寡核苷酸对 NRs 进行选择性修饰的方法，用于制备由 NPs 和纳米棒 (NRs) 组成的复杂组装体。制备了三种类型的组装体，分别命名为 End、Side 和 Satellite 异构体，其区域特异性的特征明显，产率超过 85%。多种实验方法独立验证了所制备组装体的各种结构特征、均匀性和稳定性。颗粒间的间隙存在，具有精细控制的几何参数，尺寸与细胞细胞器相当，这促使它们作为细胞内探针进行研究。与最初的预期相反，发现 End、Side 和 Satellite 异构体的 SERS 强度主要取决于超结构中 NPs 的数量，这可以通过电场模拟来合理化。将无标记的 NP-NR 组装体与 HeLa 细胞孵育表明，存在足够的场增强来检测线粒体的结构脂质和潜在的小分子代谢物。这为实时探测活细胞中局部细胞器环境的可能性提供了第一个概念验证数据。进一步的研究应包括组装体的结构优化，以实现对代谢活性的多靶标监测，并进一步提高其在变革性光学中的复杂性。
