Quantitative 3D structural analysis of small colloidal assemblies under native conditions by liquid-cell fast...

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Electron tomography is crucial for 3D nanomaterial structure analysis.
• Conventional electron microscopy requires vacuum, altering wet-prepared colloidal assemblies.
• Sample preparation for electron microscopy often changes nanoparticle organization.

Purpose of the Study:

• To develop and validate electron tomography for studying nanoparticle assemblies in their native liquid environment.
• To overcome challenges associated with in-situ electron tomography in liquid.
• To accurately characterize colloidal nanostructures without altering their native state.

Main Methods:

• Utilized a commercial liquid-cell for fast data acquisition.
• Developed a dedicated workflow for alignment and reconstruction of tomographic data from liquid samples.
• Applied the method to polystyrene-capped gold nanoparticles and self-assembled gold nanorods in aqueous media.

Main Results:

• 3D reconstructions showed less compact and more distorted configurations for nanoparticles in liquid compared to dried samples.
• Quantitative analysis revealed expanded surface-to-surface distances for gold nanorods in water versus vacuum.
• The findings align with bulk measurements, validating the in-situ method.

Conclusions:

• Electron tomography in liquid preserves the native colloidal environment of nanostructures.
• This technique provides more accurate 3D structural information than traditional vacuum-based methods.
• Developing high-resolution characterization tools that maintain the native environment is essential for colloidal nanostructure research.