Visualizing gold nanoparticle uptake in live cells with liquid scanning transmission electron microscopy

Area of Science:

• Nanotechnology
• Cell Biology
• Materials Science

Background:

• Investigating nanoparticle interactions with biological systems is crucial for understanding their potential applications and safety.
• Eukaryotic cells provide a complex environment for studying nanoparticle uptake and intracellular trafficking.

Purpose of the Study:

• To investigate the nanoscale intracellular uptake and localization of 30 nm gold nanoparticles (Au-NPs) in live eukaryotic cells.
• To quantify the interaction of Au-NPs with cellular vesicles and their subsequent aggregation.

Main Methods:

• Live COS-7 cells were cultured in a microfluidic chamber for controlled environmental conditions.
• Scanning transmission electron microscopy (STEM) was employed for high-resolution nanoscale imaging.
• Quantitative image analysis was performed to assess Au-NP binding and vesicle occupancy.

Main Results:

• Au-NPs were observed to bind to the membranes of intracellular vesicles, potentially lysosomes.
• These vesicles occupied a significant portion (67%) of the available membrane surface area.
• After 24 hours, vesicles containing Au-NPs accumulated into micrometer-sized clusters, with analyzed clusters containing 117 ± 9 and 164 ± 4 vesicles.

Conclusions:

• 30 nm Au-NPs are readily internalized by eukaryotic cells and associate with vesicular structures.
• Au-NP accumulation within vesicles leads to the formation of significant intracellular clusters over time.
• The findings provide nanoscale insights into nanoparticle-cell interactions and intracellular fate.