Combinatorial Approach to Find Nanoparticle Assemblies with Maximum Surface-Enhanced Raman Scattering

Abstract

Plasmonic nanoparticles exhibit unique properties that distinguish them from other nanomaterials, including vibrant visible colors, the generation of local electric fields, the production of hot charge carriers, and localized heat emission. These properties are particularly enhanced in the narrow nanogaps formed between nanostructures. Therefore, creating nanogaps in a controlled fashion is the key to achieving a fundamental understanding of plasmonic phenomena originating from the nanogaps and developing advanced nanomaterials with enhanced performance for diverse applications. One of the most effective approaches to creating nanogaps is to assemble individual nanoparticles into a clustered structure. In this study, we present a fast, facile, and highly efficient method for preparing core@satellite (CS) nanoassembly structures using gold nanoparticles of various shapes and sizes, including nanospheres, nanocubes (AuNCs), nanorods, and nanotriangular prisms. The sequential assembly of these building blocks on glass substrates allows us to obtain CS nanostructures with a 100% yield within 4 h. Using 9 different building blocks, we successfully produce 16 distinct CS nanoassemblies and systematically investigate the combinations to search for the highest Raman enhancement. We find that the surface-enhanced Raman scattering (SERS) intensity of AuNC@AuNC CS nanoassemblies is 2 orders of magnitude larger than that of other CS nanoassemblies. Theoretical analyses reveal that the intensity and distribution of the electric field induced in the nanogaps by plasmon excitation, as well as the number of molecules in the interfacial region, collectively contribute to the unprecedentedly large SERS enhancement observed for AuNC@AuNC. This study not only presents a novel assembly method that can be extended to produce many other nanoassemblies but also identifies a highly promising SERS material for sensing and diagnostics through a systematic search process.

Rapid formation of gold core–satellite nanostructures using Turkevich-synthesized satellites and dithiol linkers: the do's and don'ts for successful assembly

“…14,[18][19][20][21][22][23][24][25][26] Nanospheres, 14,18,19 nanorods, [20][21][22] nanocubes, 23 nanotriangles, 24 and nanostars 25,26 have, for example, all been demonstrated as core materials utilizing either Au or Ag nanostructures as component materials. In another impressive demonstration, Trinh et al 27 forwarded a combinatorial approach that realizes a complex assortment of substrate-based core-satellite structures from nine different building blocks. With such variability, it is not surprising that core-satellite structures have been demonstrated in a range of applications that include biological sensing, [28][29][30][31] bioimaging, 32,33 targeted drug release, 30 surfaceenhanced Raman scattering (SERS), [34][35][36] surface-enhanced uorescence, 37 temperature activated plasmonics, 22 plasmonic rulers, 38,39 catalysis, 40 and colorimetric, [41][42][43] chiroptical, 44 and refractive index chemical sensors.…”

“…Once formed, the core-satellite structures can be released from the substrate into a liquid medium through sonication. The same group has since used this technique to carry out a series of important demonstrations 27,35,51,52 and others have both adopted and adapted this successful strategy. 36,40,43,46,48 The satellite component of core-satellite structures is typically obtained using the Turkevich method.…”

Development of Au Nanoparticle Two-Dimensional Assemblies Dispersed with Au Nanoparticle-Nanostar Complexes and Surface-Enhanced Raman Scattering Activity

“…Furthermore, gold nanostars (AuNSs), which possess a star-shaped structure, not only induce significant local electromagnetic fields through their LSP resonance [22,23] but also have the potential to exhibit even stronger fields when coupled with the LSP resonance of AuNPs in the AuNPs/AuNSs complexes [24,25]. On the other hand, many of the morphologies used in these studies involve heterodimer structures where two nanoparticles are brought into close proximity [13,14], or core-satellite structures [26]. These structures are suitable for studying the fundamental properties of plasmon coupling, but their application as SERS platforms that utilize the strong electromagnetic field spaces is challenging.…”