Resonant Rayleigh light scattering of single Au nanoparticles with different sizes and shapes

Abstract

Scientific interest in nanotechnology is driven by the unique and novel properties of nanometer-sized metallic materials such as the strong interaction between the conductive electrons of the nanoparticles and the incident light, caused by localized surface plasmon resonances (LSPRs). In this article, we analysed the relationship of the Rayleigh scattering properties of a single Au nanoparticle with its size, shape, and local dielectric environment. We also provided a detailed study on the refractive index sensitivity of three types of differently shaped Au nanoparticles, which were nanospheres, oval-shaped nanoparticles and nanorods. This study helps one to differentiate the Rayleigh light scattering from individual nanoparticles of different sizes and/or shapes and precisely obtain quantitative data as well as the correlated optical spectra of single gold nanoparticles from the inherently inhomogeneous solution of nanoparticles. These results suggest that the shape, size and aspect ratio of Au nanoparticles are important structural factors in determining the resonant Rayleigh light scattering properties of a single Au nanoparticle such as its spectral peak position, scattering-cross-section and refractive index sensitivity, which gives a handle for the choice of gold nanoparticles for the design and fabrication of single nanosensors.

Development of Individual Plasmonic Nanosensors for Clinical Diagnosis

“…Another property of Au nanorods which ones should notice is that, if the aspect ratio of the Au nanorods is too large, the wavelength shift of the resonant Rayleigh light scattering spectrum will be higher than 800 nm after the adsorption or binding of biological materials, which is over the wavelength coverage of the micro-spectroscopy system. Therefore, the nanoparticle size and its spectral peak position must be selected with care to ensure sufficient signal intensity for LSPR assays [21,26]. These results indicate that the shape, size and aspect ratio of single Au nanoparticles determine the resonant Rayleigh light scattering properties such as the peak position, scatteringcross-section and the refractive index sensitivity, which gives a handle for the choice of Au nanoparticles for the design and fabrication of single Au nanoparticle sensors.…”

“…A deep understanding of the optical properties of noble nanoparticles allows one to develop practical applications [18,25]. Recently, Truong et al have analysed the relationship of the Rayleigh scattering properties of a single Au nanoparticle with its size, shape, aspect ratio and local dielectric environment by the dark-field micro-spectroscopy system [26]. They provided a detailed study on the refractive index sensitivity of three types of differently shaped Au nanoparticles, which were nanospheres, ovalshaped nanoparticles and nanorods.…”

“…The LSPR λ max shift was calculated as follows: Δλ max = λ max (after binding) -λ max (before binding). Further details of the experimental method and LSPR instrumentation for single nanoparticles have been previously reported [21,26,27].…”

“…The optimal Au nanosphere size, which is suitable for LSPR sensing with single Au nanoparticle as determined by its spectral peak position, scattering cross-section and refractive index sensitivity, was ∼50 nm. The ∼50 nm Au nanoparticle has green scattering color in terms of sensing application, which is the most sensitive color to the human eyes, and it enables visible colorimetric shifts from green (∼560 nm) to orange (>630 nm) via the observation of scattered light by the naked eye under a dark-field microscope owing to chemical adsorption and plasmon coupling of the nanoparticles [26,27]. In case of oval-shaped Au nanoparticles or Au nanorods, the resonant Rayleigh light scattering properties depend on their aspect ratios, and the plasmonic sensitivity increases proportionally as a function of the aspect ratio.…”

Immunoassay for netrin 1 via a glassy carbon electrode modified with multi-walled carbon nanotubes, thionine and gold nanoparticles

“…It is reported that the size of gold nanoparticle (AuNP) has an unavoidable effect on the contact area between gold nanoparticle and biomolecules [28]. Thus, we had chosen a diameter of approximate 16 nm.…”