Shape and Size Measurements of Gold Nanoparticle Suspensions

Gold nanoparticles are used in many applications, such as cosmetics, coatings and drug delivery - often in very low concentrations. The final product performance is based not just on the nanoparticles’ chemical nature, but also on their size, shape and specific surface area. It is hence important to quantify and control these key parameters.

Small Angle X-ray Scattering (SAXS) is a non-destructive method for material structure determination with minimal sample preparation. It offers information that is statistically relevant over a large volume of sample, making it a useful complimentary technique to imaging-based analysis which offer localized information.

SAXS is capable of size and shape measurement of nanoparticles with a particle size from 1 to 250nm.

Measurements and Results

SAXS measurements were performed on a gold nanoparticle suspension with a 2.5mM citrate (pH 6.9) buffer solution, using the Nano-inXider laboratory SAXS system.

The single-dimension curve after buffer subtraction is shown in Figure 1.

1D SAXS curve from gold nanoparticles suspension sample

Figure 1. 1D SAXS curve from gold nanoparticles suspension sample

The precise size and shape of the nanoparticles can be determined using data modelling. The applied model (SASfit 0.94.2, Kohlbrecher and Bressler) includes a sphere of radius R = 6.86nm, with a polydispersity equal to 1.21% using a lognormal distribution law. Figure 1 shows the fitting curve (black) and it matches with the experimental data.

A graphical representation of the gold nanoparticle sample size distribution is shown in Figure 2.

Size distribution profile.

Figure 2. Size distribution profile.


The study of nanoparticles with different sizes and shapes is achievable in the lab using the Nano-inXider. The accuracy of the collected data enables to identify bimodal population and the associated size distribution.

This information has been sourced, reviewed and adapted from materials provided by Xenocs.

For more information on this source, please visit Xenocs.

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