Aggregation behavior of amphiphilic gold nanoparticles: In silico analysis of SAXS data
Date:
Small-angle scattering (SAS) techniques are widely used nowadays because of their potential to structurally characterize nanoscale systems. They allow, in principle, to get information both about the internal structure (size, shape, and size distribution) of diverse entities, such as colloidal particles, polymers, biological macromolecules, or nanoparticles, and also about their mutual interparticle interactions and aggregation capability. However, extracting this valuable information from the scattering intensities typically recorded in this kind of experiments is not an easy task as it requires to analyze and interpret noisy data collected in a very limited region of the reciprocal space.
Indirect Fourier Transformation (IFT) methodologies are the most commonly used tools to reveal self-scattering structural details from data obtained using very diluted samples as they enable to reconstruct, under very few assumptions, the corresponding pair distance distribution function (PDDF), which contains all the information regarding the morphology of the particles in the real-space. On the other hand, the current approaches to study interparticle interference effects rely on estimating the so-called structure factor, which encloses all the interparticle contributions to the scattering curve, by using interaction model potentials and liquid-state theories. As a consequence, these strategies are therefore dependent on parameters fitting and very strong and not always valid assumptions.
For those reasons, the usage of a specific model potential in the analysis of SAS intensities can induce to erroneous reasoning about the spatial particle distribution or the origin of interparticle interference effects, for instance, and therefore the conclusions obtained from this kind of analyses must be taken with care. To circumvent the limitations associated with the aforementioned strategies, in this contribution, I will describe a model-free protocol that allows the inference of interaction potentials from small-angle scattering data without requiring strong predefined assumptions. I will also show how this protocol can be applied to investigate the aggregation behavior of amphiphilic gold nanoparticles.