Simultaneous Sizing and Refractive Index Analysis of Heterogeneous Nanoparticle Suspensions

Area of Science:

• Nanosciences
• Materials Science
• Biotechnology

Background:

• Characterizing heterogeneous nanoparticle suspensions is crucial but challenging for existing methods.
• Current techniques struggle with polydisperse samples due to indistinguishable signals from particles of varying sizes and compositions.

Purpose of the Study:

• Introduce holographic nanoparticle tracking analysis (holoNTA) for accurate characterization of heterogeneous nanoparticle suspensions.
• Develop a method to decouple particle size and material refractive index contributions for precise sizing.

Main Methods:

• Combined high dynamic range k-space imaging with holographic 3D single-particle tracking.
• Utilized an extended imaging volume for long-term particle tracking and improved trajectory data.
• Determined nanoparticle refractive index and hydrodynamic size from scattering amplitude and diffusion coefficient.

Main Results:

• HoloNTA successfully characterized both homogeneous and heterogeneous nanoparticle suspensions (40-250 nm).
• Demonstrated improved sizing sensitivity irrespective of localization uncertainty and particle size.
• Monitored protein corona formation, distinguishing complexes from different proteins (avidin, BSA, streptavidin).

Conclusions:

• HoloNTA provides a straightforward, sensitive, and accurate method for analyzing heterogeneous nanoparticle samples.
• The technique enables precise quantification and sizing of individual nanoparticles, crucial for various scientific applications.
• HoloNTA is expected to have broad applications in fundamental and applied research requiring routine nanoparticle analysis.