Shape and Size Measurements of Gold Nanoparticles
Gold nanoparticles hold many applications in various areas, such as coatings, cosmetics and drug delivery – usually in extremely low concentrations. The ultimate product performance is based on the nanoparticles’ chemical nature, as well as their shape, size, and specific surface area. Quantifying and controlling these key parameters is therefore essential.
Small Angle X-ray Scattering (SAXS) is a non-destructive method that enables material structure determination with minimal sample preparation. It provides statistically relevant information over a large volume of sample, making it a valuable complimentary technique to imaging-based analysis which provides localized information.
SAXS can measure size and shape of nanoparticles with particle sizes ranging from 1 to 250 nm.
The Nano-inXider laboratory SAXS system was used to perform SAXS measurements on a gold nanoparticle suspension with a 2.5 mM citrate (pH 6.9) buffer solution.
Figure 1 shows the single-dimension curve after buffer subtraction.
Figure 1. 1D SAXS curve from gold nanoparticles suspension sample.
The precise shape and size of the nanoparticles can be established with the help of data modeling. The applied model (SASfit 0.94.2, Kohlbrecher and Bressler) includes a sphere of radius R = 6.86 nm, with a polydispersity equal to 1.21% using a lognormal distribution law. Figure 1 depicts the fitting curve (black), which matches with the experimental data.
Figure 2 shows a graphical representation of the gold nanoparticle sample size distribution.
Figure 2. Size distribution profile.
The study of nanoparticles with different shapes and sizes can be achieved in the laboratory using the Nano-inXider. The accuracy of the collected data makes it possible to identify bimodal population and the associated size distribution.
This information has been sourced, reviewed and adapted from materials provided by Xenocs.
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