Flow Dichroism as a Reliable Method to Measure the Hydrodynamic Aspect Ratio of Gold Nanoparticles

Abstract

Particle shape plays an important role in controlling the optical, magnetic and mechanical properties of nanoparticle suspensions as well as nanocomposites. However, characterizing the size, shape and the associated polydispersity of nanoparticles is not straightforward. Electron microscopy provides an accurate measurement of the geometric properties, but sample preparation can be laborious and to obtain statistically relevant data many particles need to be analyzed. More importantly practical applications are not always governed by the geometric properties but rather by hydrodynamic properties. Methods that evaluate the dynamics of nanoparticles such as light scattering and rheo-optical methods accurately provide hydrodynamic properties, but do necessitate a sufficient optical response. In the present work, different

In Situ Determination of Colloidal Gold Concentrations with UV–Vis Spectroscopy: Limitations and Perspectives

“…However, UV-Vis spectra of GNPs with equal Au(0) concentration are normalized at 400 nm occasionally and in general without further explanation. 44,54,55,[58][59][60][61][62] It has to be noted that in these publications, the GNPs have different sizes, shapes and surface modifications. This paper evaluates the determination of the absolute Au(0) concentration in aqueous GNP solution applying the Abs 400 .…”

Challenges and opportunities in the advancement of nanomedicines

“…In some cases, shape analysis can be performed on particle dispersions with low nanometer resolution using small-angle X-ray or neutron scattering (SAXS or SANS), but intensive computational modeling is still required [71]. However, it should be noted that new methods for particle shape analysis continue to emerge [72], with the potential to become practical technologies.…”

Nonspherical nanoparticles characterization by partially depolarized dynamic light scattering

“…The efficiency of NP using depends strongly on their shape and size, so it is very important to measure the particle's geometrical parameters: length, diameter, aspect ratio (ratio of length to diameter) at different stages of their synthesis and application [1]. Aspect ratio (AR) is also of interest for the study of the NP toxic properties, due to strongly influences of AR on particles ability to penetrate biological barriers.…”

“…Physico-chemical methods, primarily optical, require relatively inexpensive equipment, substantially less time for the sample preparation and analysis, allows to automate the analysis procedure. Such optical method, as depolarized dynamic light scattering (DDRS), was used in a number of studies for control of the geometric parameters of non-spherical NP [1][2][3][4][5][6]. The method is based on the detection of intensity fluctuations of the scattered light by the particles moving under the influence of Brownian motion in a liquid.…”

“…DRS method was used for measuring geometrical parameters of gold nanoparticles [1,3,4] and carbon nanotubes [2,5]. The main limitation of DDRS is the need of measurement of very weak optical signals for registration depolarized component of scattered light (components VH).…”