Unique Gold Nanoparticle Aggregates as a Highly Active Surface-Enhanced Raman Scattering Substrate

Abstract

A unique gold nanoparticle aggregate (GNA) system has been shown to be an excellent substrate for surface-enhanced Raman scattering (SERS) applications. Rhodamine 6G (R6G), a common molecule used for testing SERS activity on silver, but generally difficult to detect on gold substrates, has been found to readily bind to the GNA and exhibit strong SERS activity due to the unique surface chemistry afforded by sulfur species on the surface. This GNA system has yielded a large SERS enhancement of 107−109 in bulk solution for R6G, on par with or greater than any previously reported gold SERS substrate. SERS activity has also been successfully demonstrated for several biological molecules including adenine, l-cysteine, l-lysine, and l-histidine for the first time on a gold SERS substrate, showing the potential of this GNA as a convenient and powerful SERS substrate for biomolecular detection. In addition, the SERS spectrum of R6G on single aggregates has been measured. We have shown that the special surface properties of the GNA, in conjunction with strong near-IR absorption, make it useful for SERS analysis of a wide variety of molecules.

Gold nanoparticles explore cells: Cellular uptake and their use as intracellular probes

“…In SERS, the otherwise extremely weak Raman scattering signal [8] is enhanced by several orders of magnitude by ensuring that the molecule is in very close vicinity of nanoparticles or of a nanostructured gold or silver surface [7,9,10]. The SERS spectrum is a vibrational 'fingerprint' which characterises the chemical bonds and symmetry of the molecule.…”

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

“…Aggregates, which are random assemblies of nanoparticles, can have multiple resonances depending on their size and shape, especially when the interaction between particles is strong [18,53,56,57]. This is also true for triangles, stars, cubes and cages [37,42,46,48,58].…”

“…These structures showed broadening of the total extinction indicative of a polydispersed ensemble [56]. While these morphologies and extended spatial arrangements may benefit an application like SERS, where aggregation and particle alignment generate hot spots which enhance scattering, a more monodispersed population is desired for applications like photothermal therapies that require enhanced resonance with incident laser light for greater efficiency of heat generation and transfer [127].…”

“…The highly localized EM field of the metal, due to SPR, is known to enhance the Raman signal by 5-10 orders of magnitude [273][274][275][276]. Aggregation of metal nanoparticles can also be employed to produce significant SERS enhancement through the generation of hot spots which result from EM coupling between particles in near field proximity to one another [56,64,182,198,277,278].…”

Feature‐based recognition of Surface‐enhanced Raman spectra for biological targets

“…While R6G is a reference molecule for SERS measurements on silver substrates, it is known that its response on gold is harder to detect [20,21]. This makes it an ideal candidate for our proposed automated detection, since the signal provided by this molecule is very well characterized, while not being overly simplistic to measure with GNPs.…”