A solution-based nano-plasmonic sensing technique by using gold nanorods

Abstract

We have successfully demonstrated a novel sensing technique for monitoring the variation of solution concentrations and measuring the effective dielectric constant in a medium by means of an ultra-small and label-free nanosensor, the mechanism of which is based on the localized surface plasmon resonance (LSPR) of gold nanorods. The nanorods are fabricated in a narrow size distribution, which is characterized by transmission electron microscopy and optical absorption spectroscopy. In addition, we employ a simple analytical calculation to examine the LSPR band of the absorption spectrum, which provides excellent consistency with aspect ratio. The plasmonic sensing is performed by detecting the diffusion process and saturation concentration of hexadecyltrimethylammonium bromide in water, and tracing the effective dielectric constants of the medium simultaneously. This promising sensing and analytical technique can be easily used for investigating the nano-scale variations of mixing or reaction process in a micro/nanofluidic channel or the biological interaction in the cytoplasm of the cell.

Surface-Enhanced Resonance Raman Scattering of Rhodamine 6G in Dispersions and on Films of Confeito-Like Au Nanoparticles

“…They can efficiently absorb the light at a specific band, and their optical behavior is today understood as a resonance of collective motion of surface electrons with the incident light [ 1 , 2 , 3 ]. This phenomenon, named localized surface plasmon resonance (LSPR), depends on many factors like the size and morphology of the nanoparticles and the dielectric constant of the surrounding medium [ 1 , 2 , 3 , 4 ], and the changes in these factors cause the shift and intensification of plasmon absorption band of the nanoparticles. Thus, the LSPR phenomenon is used in sensing devices, as the stimulation changes the color of nanoparticles [ 5 ].…”

“…On the contrary, the motion of electrons on the surface can affect the other materials adjacent to the nanoparticle. The incident light polarizes the nanoparticle through the LSPR, and it provides the oscillating electric field around the nanoparticle [ 1 , 2 , 3 , 4 , 5 , 6 ]. Then, the materials on the nanoparticle can be strongly excited by this localized electric field.…”

Fluorescence Quenching of Uranine on Confeito-Like Au Nanoparticles

“…1 Today, their optical phenomena are explained by a collective motion of free electrons on the nanoparticles (i.e., localized surface plasmon, LSP). 1 The LSP depends on the size and shape of nanoparticles, [2][3][4] and the resonance of LSP with incident light have been applied as optical devices. 5 The LSP also can influence optical properties of materials in the vicinity of nanoparticle, and a typical effect of the LSP is the surfaceenhancing on Raman scattering 5 6 and infrared-absorption spectra.…”

Polysiloxanes Modified by Thiol‐Ene Reaction and Their Interaction with Gold Nanoparticles

“…The wavelength shift is usually small compared to the shift due to aggregation but can bring information on the surrounding of the nanoparticles. Accordingly, the SPR band is affected by the solvent refractive index, by organic layers, either well‐organized monolayers, surfactants or polymers, wrapping the nanoparticle. When this organic layer is stimuli‐responsive, the SPR band shifts with the application of the stimulus.…”