Size-dependent cellular uptake and localization profiles of silver nanoparticles

Area of Science:

• Nanotechnology
• Cell Biology
• Materials Science

Background:

• Silver nanoparticles (AgNPs) are widely used as antibacterial agents.
• Particle size is a critical factor for AgNP cellular interactions, but its precise role in uptake remains debated.
• Understanding AgNP uptake mechanisms is crucial for their safe and effective application.

Purpose of the Study:

• To investigate the size-dependent cellular uptake of silver nanoparticles (AgNPs) in B16 cells.
• To elucidate the specific endocytic pathways involved in AgNP internalization based on particle size.

Main Methods:

• Quantification of AgNP uptake using inductively coupled plasma-mass spectrometry (ICP-MS).
• Visualization of AgNP internalization via transmission electron microscopy (TEM).
• Inhibition studies using specific endocytosis pathway blockers: chlorpromazine hydrochloride, methyl-β-cyclodextrin, and 5-(N-ethyl-N-isopropyl) amiloride.

Main Results:

• AgNP uptake efficiency varied with size, with 20 nm and 100 nm AgNPs showing the lowest and highest uptake, respectively.
• Smaller AgNPs (5 nm) rapidly distributed into cytoplasm and nucleus, while larger ones (100 nm) showed slower nuclear entry.
• AgNP internalization was primarily mediated by clathrin-mediated endocytosis, with contributions from caveolin-mediated endocytosis and macropinocytosis depending on particle size.

Conclusions:

• AgNP size dictates both the efficiency and the primary endocytic pathway for cellular uptake in B16 cells.
• Clathrin-mediated endocytosis appears to be the dominant pathway for most AgNP sizes.
• These findings highlight the importance of considering AgNP size for predicting their biological fate and interactions.