Analysis of 4D-STEM methods for detecting metallic nanoparticles in amorphous ice: A numerical study

Area of Science:

• Materials Science
• Biophysics
• Microscopy

Background:

• Metallic nanoparticles are crucial for medical imaging and therapies.
• Understanding nanoparticle-cell interactions is key for medical applications.
• Cryo-scanning transmission electron microscopy (Cryo-STEM) is vital for studying beam-sensitive biological systems.

Purpose of the Study:

• To develop methods for detecting metallic nanoparticles within biological samples using Cryo-STEM.
• To overcome the challenge of nanoparticle visibility obscured by surrounding vitrified ice.

Main Methods:

• Utilized extended ptychographic iterative engine (ePIE), non-negative matrix factorization (NMF), and virtual dark-field imaging algorithms.
• Tested detection across various ice thicknesses and electron beam fluxes.
• Applied methods to metallic nanoparticles embedded in ice slabs.

Main Results:

• Successfully demonstrated the detection of metallic nanoparticles in vitrified ice.
• Showcased the effectiveness of the developed algorithms under different experimental conditions.
• Improved nanoparticle visibility in bright-field Cryo-STEM images.

Conclusions:

• The developed algorithms enhance the detection of metallic nanoparticles in biological samples via Cryo-STEM.
• This advancement is critical for the future development of nanoparticle-based medical diagnostics and therapeutics.
• Improved visualization facilitates better understanding of nanoparticle-cell interactions.