Quantitative uptake of colloidal particles by cell cultures

Area of Science:

• Nanotechnology
• Materials Science
• Toxicology

Background:

• The increasing use of nano- and microparticles in technology necessitates a thorough understanding of their biological interactions.
• Colloidal particles can pose risks to human health and the environment, but their complex interactions with biological systems are not fully understood.
• Current nanosafety research faces challenges due to the multitude of parameters influencing particle behavior in biological environments.

Purpose of the Study:

• To provide an overview of common denominators and propose universal metrics for assessing the safety of colloidal particles.
• To discuss how biological media affect particle properties, cellular uptake mechanisms, and particle fate.
• To highlight the importance of accurate quantification and characterization in nanosafety studies.

Main Methods:

• Review of existing literature on colloidal particle interactions with biological systems.
• Discussion of methods to distinguish internalized from membrane-attached particles.
• Exploration of correlations between physicochemical properties and cellular uptake.

Main Results:

• In typical exposure scenarios, a significant portion of colloidal particles remain attached to cell membranes rather than being internalized.
• Quantitative uptake studies must differentiate between adherent and internalized particles to avoid false positives.
• The choice of metrics (e.g., particle number vs. volume) significantly impacts uptake study results.

Conclusions:

• pH-sensitive fluorophores offer a potential solution for accurately distinguishing internalized particles by differentiating endosomal/lysosomal environments from extracellular ones.
• Colloidal particle properties can change throughout their lifecycle, requiring characterization at different stages.
• Developing universal metrics is essential for reliable nanosafety assessments.