Silica Nanosprings Coated with Noble Metal Nanoparticles: Highly Active SERS Substrates

Abstract

Silica nanosprings with large surface-to-volume ratios were coated with noble metal nanoparticles (NPs) using chemical vapor deposition or chemisorption of presynthesized or in situ synthesized nanoparticles. Chemisorption of presynthesized silver NPs onto amine-functionalized silica NS results in particularly interesting materials with small interparticle spacings and high surface-enhanced Raman scattering activity. SERS enhancement factors approaching ∼10 10 were observed with thiophenol. In an alternative approach, silica NS coated with core-shell nanostructures, formed by deposition of catalytically reduced silver on AuNP-coated NS, exhibit a highly uniform SERS response with enhancement factors of ∼10 8 . The advantages of these materials include (i) commercial availability of silica nanosprings, AuNPs/AgNPs, and silver enhancer solutions, (ii) simplicity and reproducibility of functionalization and deposition steps, and (iii) high SERS activity of these substrates rendering them of considerable interest for a variety of sensor applications.

Noble metal/silica “raspberry” type hybrids: Synthesis and functionalization

“…[13,[19][20][21]. For instance Sai et al [19] have coated noble metals like Au and Ag on amine functionalized SiO 2 nanosprings (helical nanowires), which showed high surface-enhanced Raman spectroscopy activity, useful in sensor applications.…”

“…[13,[19][20][21]. For instance Sai et al [19] have coated noble metals like Au and Ag on amine functionalized SiO 2 nanosprings (helical nanowires), which showed high surface-enhanced Raman spectroscopy activity, useful in sensor applications. Du and He [21] have prepared a composite containing metal NPs (Au, Pd, Pt and Au and Pt) immobilized into amino functionalized mesoporous SiO 2 NPs and it has been investigated for the catalytic reduction of 2-nitroaniline.…”

Nanosprings harvest light more efficiently

“…However, nanotechnology provides versatile design options that may have even more effective absorption capability than cylindrical geometry. Nanosprings are emerging as an optical nanoelement and can be used in different photonics applications [24][25][26][27][28][29]. A nanospring scheme is demonstrated to have significant potential in 1D nanostructure-based optoelectronics and many advantageous features compared with nanowire geometry.…”

Dewetting process of Au films on SiO2 nanowires: Activation energy evaluation

“…On the other hand, the decoration of SiO 2 NWs by metal films or nanoparticles (NPs) can greatly enhance their performances (as sensitive detection, photovoltaic efficiency, Raman response) due to local plasmonic effects [19][20][21][22][23]. In particular, surface enhanced Raman spectroscopy effects in metal NPs/SiO 2 NWs are extremely promising for diagnostics with rapid screening [20] and monitoring of drug recipient interaction in pharmaceuticals [24].…”