Processing pathway dependence of amorphous silica nanoparticle toxicity: colloidal vs pyrolytic

Area of Science:

• Materials Science
• Nanotechnology
• Toxicology

Background:

• Amorphous silica nanoparticles (NPs) are synthesized via different routes, leading to varied properties.
• Understanding structure-toxicity relationships is crucial for NP safety assessment.

Purpose of the Study:

• To investigate the structure/toxicity relationships of amorphous silica NPs.
• To compare the toxicity of colloidal (Stöber) and fumed silica NPs.

Main Methods:

• Spectroscopic and physical analyses to characterize NPs (aggregation, hydroxyl concentration, siloxane rings, radical generation).
• Erythrocyte hemolytic assays and cell viability/ATP level assessments (epithelial, macrophage cells).

Main Results:

• Fumed silica NPs showed toxicity correlated with hydroxyl concentration, ROS generation, and red blood cell hemolysis.
• Colloidal silica NPs were essentially non-toxic under identical conditions.
• Fumed silica toxicity linked to strained siloxane rings, chainlike aggregation, and hydroxyl content.

Conclusions:

• Amorphous silica NP toxicity is highly dependent on synthesis method and resulting structure/chemistry.
• Fumed silica's toxicity is attributed to its unique framework, surface chemistry, and morphology.
• Colloidal silica NPs are safer alternatives due to their distinct structural characteristics.