2D analysis of polydisperse core-shell nanoparticles using analytical ultracentrifugation
Challenge
Accurate knowledge of the size, density, and composition
of nanoparticles (NPs) is vital for their practical applications.
Analytical ultracentrifugation (AUC) provides detailed
insights into NP properties, but the interpretation becomes complicated when considering NPs
as core-shell systems, where the stabilizing shell affects the overall hydrodynamics of the
NPs.
The current state-of-the-art data evaluation methods
encounter difficulties when characterizing polydisperse and widely distributed NPs due to
either inadequate resolution or inability to accurately account for the core-shell
properties.
Most particle production methods yield polydisperse
particle size distributions (PSDs), posing challenges to high-resolution algorithms because
of the reduced experimental signal from each species.
Modern tools for simultaneous size and
effective density analysis have not been adequately applied to polydisperse and multimodal
NPs, which represent most systems in nanotechnology.
Solution
The study initiated by investigating the performance of
existing data evaluation models using simulated data.
A new methodology was proposed, based on the
parametrically constrained spectrum analysis (PCSA), to specifically address the core-shell
properties of NPs.
The PCSA method allows for detailed modeling of systems
where a systematic change in two hydrodynamic parameters describes heterogeneity. It's
specially designed for core-shell NPs, capable of analyzing broad PSDs with high resolution
while simultaneously offering insights into the core-shell characteristics.
The proposed PCSA method can even potentially address
varying shell thicknesses with NP size.
The effectiveness of this new methodology
was confirmed through experiments using ZnO and CuInS2 quantum dots, both representing
typical polydisperse core–shell NPs.
Conclusion
The study explored algorithms for sedimentation data
from polydisperse Particle Size Distributions (PSDs). Previous methods couldn't adequately
address the core-shell properties of nanoparticles (NPs). Current 2D analyses have
resolution limitations and are unsuitable for large datasets.
However, the new PCSA with a 2nd order power law
provides high resolution for core-shell properties in NPs. Tested on specific NPs, it
yielded accurate results.
These advancements broaden the applications
of AUC, and the PCSA tool is available in UltraScan3.
