Fast characterization of gold nanorods ensemble by correlating its structure with optical extinction spectral features

Abstract

Owing to unique size- and shape- dependent localized surface plasmon resonance (LSPR) of noble metal nanoparticles (NPs), the optical extinction spectroscopy method (OES) has received much attention to characterize the geometry of metal NPs by fitting experimental UV-vis-NIR spectra. In this work, we aimed to develop a more convenient and accurate OES method to characterize the structural parameters and concentration of the gold nanorods (GNRs) ensemble. The main difference between our approach and previous OES methods is that we solve this inverse spectra problem by establishing the LSPR relation equations of GNRs ensemble so that there is no need of UV-vis-NIR spectra fitting process. The aspect ratio (AR) and AR distribution can be directly retrieved from two of UV-vis-NIR spectral parameters (peak position and full width at half maximum) using the obtained relation equations. Furthermore, the relation equations are modified for applying to the more general GNRs samples by considering the plasmon shift due to the near distance dielectric sensitivity. Finally, instead of inductively coupled plasma mass spectrometry (ICP-MS) measurement, we provide a more facile measure of the mass-volume concentration which can be determined from the extinction value at 400 nm. By comparing with the experimental results, it shows that the retrieved results by the relation equations are reliable.

Photothermal Ring Integrated Intraocular Lens for High‐Efficient Eye Disease Treatment

“…For instance, gold nanomaterials have been specifically delivered and accumulated in solid tumor for killing cancer cells in a spatiotemporal way without destroying the normal tissue under NIR irradiation . Meanwhile, to prevent the coalescence of Au nanostructures, silica coated Au nanorods (Au@SiO 2 ) as an NIR laser mediated multifunctional theranostic nanoplatform for simultaneous hyperthermia therapy was developed …”

“…Furthermore, the gold nanorods were coated with silica to form core–shell structured nanorods (Au@SiO 2 ). [17d,19b] The SiO 2 coating layer not only endowed high stability of dispersion but also enabled easier conjugation of Au@SiO 2 on the rim of C‐IOLs . [13b,20] As shown in transmission electron microscopy (TEM) images (Figure S1, Supporting Information), the Au nanorod core was 56 ± 6 nm in length and 18 ± 4 nm in width, and the silica shell was estimated to have a homogeneous thickness of 15 ± 3 nm.…”

Determination of morphological characteristics of metallic nanoparticles based on modified Maxwell-Garnett fitting of optical responses

“…1). The energies of the transversal SPR mode of S2 and S3 NPs, calculated from the Fr€ ohlich condition (10), are larger or in the same order of magnitude than the interband transition threshold. In other words, the transversal plasmon mode of S2 and S3 NPs is damped by the interband transitions.…”

“…[10][11][12][13][14][15][16][17] Several authors 11,12 have proposed to determine the size distribution of spherical metallic NPs by fitting their absorption spectra with the Mie theory. 3 However, the Mie theory fails to describe the optical properties of NP with nonspherical shape.…”

“…29 This suggests that the NPs in S2 and S3, which seems to have a spherical shape in TEM images, are probably slightly flattened along the normal of the TEM grid. 29 According to the Fr€ ohlich condition 3 (10) (Fig. 1) and the (L 1 , L 2 ) distribution (Fig.…”