Kim Jae-Myoung, Kim Jiyeon, Choi Kyungin, Nam Jwa-Min
Department of Chemistry, Seoul National University, Seoul, 08826, South Korea.
Adv Mater. 2023 Apr;35(15):e2208250. doi: 10.1002/adma.202208250. Epub 2023 Feb 26.
Metal nanostructures with a tunable plasmonic gap are useful for photonics, surface-enhanced spectroscopy, biosensing, and bioimaging applications. The use of these structures as chemical and biological sensing/imaging probes typically requires an ultra-precise synthesis of the targeted nanostructure in a high yield, with Raman dye-labeling and complex assay components and procedures. Here, a plasmonic nanostructure with tunable dual nanogaps, Au dual-gap nanodumbbells (AuDGNs), is designed and synthesized via the anisotropic adsorption of polyethyleneimine on Au nanorods to facilitate tip-selective Au growths on nanorod tips for forming mushroom-shaped dumbbell-head structures at both tips and results in dual gaps (intra-head and inter-head gaps) within a single particle. AuDGNs are synthesized in a high yield (>90%) while controlling the inter-head gap size, and the average surface-enhanced Raman scattering (SERS) enhancement factor (EF) value is 7.5 × 10 with a very narrow EF distribution from 1.5 × 10 to 1.5 × 10 for >90% of analyzed particles. Importantly, AuDGNs enable label-free on-particle SERS detection assays through the diffusion of target molecules into the intraparticle gap for different DNA sequences with varying ATGC combinations in a highly specific and sensitive manner without a need for Raman dyes.
具有可调谐等离子体间隙的金属纳米结构可用于光子学、表面增强光谱学、生物传感和生物成像应用。将这些结构用作化学和生物传感/成像探针时，通常需要以高产量超精确合成目标纳米结构，并结合拉曼染料标记以及复杂的检测组件和程序。在此，通过聚乙烯亚胺在金纳米棒上的各向异性吸附，设计并合成了一种具有可调谐双纳米间隙的等离子体纳米结构——金双间隙纳米哑铃（AuDGNs），以促进纳米棒尖端的尖端选择性金生长，从而在两个尖端形成蘑菇状哑铃头结构，并在单个颗粒内产生双间隙（头内间隙和头间间隙）。AuDGNs在控制头间间隙尺寸的同时实现了高产率（>90%）合成，并且平均表面增强拉曼散射（SERS）增强因子（EF）值为7.5×10，对于>90%的分析颗粒，其EF分布非常窄，从1.5×10到1.5×10。重要的是，AuDGNs能够通过目标分子扩散到颗粒内间隙，以高度特异性和灵敏的方式对具有不同ATGC组合的不同DNA序列进行无标记颗粒上SERS检测分析，而无需拉曼染料。
