Generation of Hot Spots with Silver Nanocubes for Single‐Molecule Detection by Surface‐Enhanced Raman Scattering

Abstract

This paper presents a simple strategy for the formation of surface-enhanced Raman scattering (SERS) hot spots, or regions with extraordinary large electric-field enhancements, by depositing a silver nanocube on a metal substrate. Our experimental and theoretical results show that hot spots form at the corners of a nanocube in contact with the substrate and the hot spots derived from a single silver nanocube are capable of detecting SERS from a single molecule. By varying the electrical property of the substrate, and the distance between the nanoparticle and the substrate, we show that the substrate can dramatically affect the SERS from a supported nanoparticle. In addition, by comparing the SERS for nanocubes and nanospheres of similar sizes, we show that this effect is also sensitive to the shape of the supported nanoparticle, and enhancement factors of 9.7×10 6 and 2.1×10 8 were obtained for a nanosphere and a nanocube on a metal substrate, respectively. This new approach requires minimum fabrication efforts and offers great simplicity for the formation of robust and fully accessible hot spots, providing an effective SERS platform for single-molecule detection.

Recent advancements in plasmon-enhanced promising third-generation solar cells

“…The IPCE enhancement ratio graph clearly shows photocurrent enhancement in the 550-800-nm region of the spectrum, corresponding to the LSPR of the popcorn-shaped metal NPs (Figure 18). Au@SiO 2 nanocubes were found advantageous over spherical NPs in DSCs, as they had two times higher extinction and absorption efficiency, two times larger surface area, and higher electromagnetic field localization at edges and corners [49,30,98,99]. The edge length of Au nanocubes can be adjusted by hexadecyltrimethylammonium bromide (CTAB) ligands [100].…”

Wafer-Scale Leaning Silver Nanopillars for Molecular Detection at Ultra-Low Concentrations

“…A broad variety of SERS substrates have been fabricated over the past decade, e.g. nanorods 8 , nanocubes 9 , nanostars 10 , various particle arrays [11][12][13][14][15][16] and silver dendrites 17 . Recently electric field (E-field) enhancement factors (EF) above 10 8 to even 10 10 have been reported.…”

“…Various shapes of metallic nanoparticles in colloidal solutions showing high EFs with tunable LSPR wavelengths have been synthesized and their optical properties have been investigated both experimentally and theoretically. 9,[11][12][13][14][15][16] The main advantage of the SERS active colloidal suspensions is high EFs caused by the lightning-rod effect that is particularly pronounced in metal nanoparticles with sharp surface features. Decreasing the inter-particle separation, the LSPR coupling increases and the largest E-field enhancement values are usually obtained in the case of colloidal particle aggregates.…”

Silica-coated dimers of silver nanospheres as surface-enhanced Raman scattering tags for imaging cancer cells

“…Therefore, it should give the strongest SERS signals. Hot spots could also be created at the corner sites of a cubic core of the cube tags [42,46], leading to a higher EF than the sphere tags with spherical cores. Because the three types of tags had a similar major LSPR peak (figure 2d ), the possibility of wavelength-dependent enhancement [43], where the SERS activity is maximized when the excitation source matched the LSPR peak of the tags, could be neglected.…”