Gold Nanoparticle Quantitation by Whole Cell Tomography.

Area of Science:

• Biomedical Engineering
• Materials Science
• Cell Biology

Background:

• Biomedical applications of engineered gold nanoparticles necessitate precise control over cellular uptake.
• Understanding nanoparticle quantity and distribution within cells is crucial for targeted therapies and diagnostics.

Purpose of the Study:

• To accurately characterize the number and spatial distribution of gold nanoparticles within individual mammalian stem cells.
• To develop and validate a multiscale imaging approach for cellular nanoparticle analysis.

Main Methods:

• Utilized fast focused ion beam-scanning electron microscopy (FIB-SEM) based tomography for high-resolution imaging.
• Employed enhanced optical microscopy for multiscale sample mapping and cell identification.
• Confirmed cross-section accuracy with transmission electron microscopy (TEM) and scanning helium ion microscopy (SHIM).

Main Results:

• Quantified gold nanoparticle numbers and spatial distribution within individual mammalian stem cells.
• Investigated the impact of slice thickness on particle and cluster counting accuracy.
• Determined nanoparticle cluster packing volume, finding it to be 2.15 ± 0.20 times the volume of bare gold nanoparticles for 60 nm citrate-stabilized particles.

Conclusions:

• Established a robust method for quantifying intracellular gold nanoparticles using FIB-SEM tomography.
• Provided critical data on nanoparticle loading and spatial arrangement within stem cells, essential for optimizing biomedical applications.
• Highlighted the importance of considering nanoparticle packing density in cluster formation.