通过将DNA折纸纳米叉与球形和非球形Au或Ag纳米颗粒相结合,提出了用于表面增强拉曼散射(SERS)的等离子纳米颗粒二聚体的通用生成。将不同的纳米粒子与DNA折纸纳米叉结合形成DNA折纸纳米天线(DONA),等离子体纳米颗粒二聚体可以针对SERS中的特定激发波长进行优化。这样的纳米颗粒二聚体的制备是足够稳健的,以使得能够通过测量来自五种不同二聚体设计的总共数千个二聚体来在单个二聚体水平上表征染料修饰的DONA的SERS强度和SERS增强因子。每个用三种不同的拉曼报告分子官能化并在四种不同的激发波长下测量。基于这些数据,已经针对每个二聚体设计和激发波长确定了SERS增强因子(EF)分布。具有最高EF的结构和测量条件适用于单分子SERS(SM-SERS),这是通过将单个染料分子置于热点中来实现的。我们证明了将单分子置于SM-SERS的强烈增强热点的可能性可以通过使用具有几个尖锐边缘的各向异性纳米颗粒来增加。比如纳米花。在一个二聚体结构中组合Ag纳米颗粒与Au颗粒允许覆盖几乎整个可见光范围的宽带激发。用于SERS的最通用的等离子体二聚体结构将球形Ag纳米颗粒与Au纳米花结合在一起。采用不连续Galerkin时域方法,我们从数字上调查裸露的,关于光谱和近场特性的对称二聚体,证明这一点,的确,纳米花诱导多个热点位于边缘,超过球形二聚体的强度,表明SM-SERS的可能性。所呈现的DONA结构和SERS数据为应用此类设计作为通用SERS标签和作为SM-SERS测量的基底提供了稳健的基础。
A versatile generation of plasmonic nanoparticle dimers for surface-enhanced Raman scattering (SERS) is presented by combining a DNA origami nanofork and spherical and nonspherical Au or Ag nanoparticles. Combining different nanoparticle species with a DNA origami nanofork to form DNA origami nanoantennas (DONAs), the plasmonic nanoparticle dimers can be optimized for a specific excitation wavelength in SERS. The preparation of such nanoparticle dimers is robust enough to enable the characterization of SERS intensities and SERS enhancement factors of dye-modified DONAs on a single dimer level by measuring in total several thousands of dimers from five different dimer designs, each functionalized with three different Raman reporter molecules and measured at four different excitation wavelengths. Based on these data, SERS enhancement factor (EF) distributions have been determined for each dimer design and excitation wavelengths. The structures and measurement conditions with the highest EFs are suitable for single-molecule SERS (SM-SERS), which is realized by placing single dye molecules into hot spots. We demonstrate that the probability of placing single molecules in a strongly enhancing hot spot for SM-SERS can be increased by using anisotropic nanoparticles with several sharp edges, such as nanoflowers. Combining a Ag nanoparticle with a Au particle in one dimer structure allows for a broadband excitation covering almost the whole visible range. The most versatile plasmonic dimer structure for SERS combines a spherical Ag nanoparticle with a Au nanoflower. Employing the discontinuous Galerkin time domain method, we numerically investigate the bare, symmetric dimers with respect to spectral and near-field properties, showing that, indeed, the nanoflowers induce multiple hot spots located at the edges which surpass the intensity of the spherical dimers, indicating the possibility for SM-SERS. The presented DONA structures and SERS data provide a robust basis for applying such designs as versatile SERS tags and as substrates for SM-SERS measurements.