Multiwalled carbon nanotube dispersion methods affect their aggregation, deposition, and biomarker response

Area of Science:

• Environmental Science
• Nanotechnology
• Toxicology

Background:

• Multiwalled carbon nanotubes (MWNTs) are increasingly used, necessitating understanding their environmental fate.
• Dispersion methods significantly influence nanoparticle behavior in aquatic environments.

Purpose of the Study:

• To evaluate the impact of dispersion methods (ultrasonication vs. long-term stirring) on MWNTs.
• To assess how surfactants and natural organic matter (NOM) affect MWNT dispersion and properties.
• To investigate the aggregation and deposition behaviors of dispersed MWNTs.

Main Methods:

• MWNTs were dispersed using ultrasonication (SON) and long-term stirring (LT) with surfactants (SDS, Pluronic) and NOM (humic acid, fulvic acid).
• Physicochemical properties (surface charge, size, morphology) of MWNT suspensions were analyzed.
• Aggregation and deposition behaviors were studied, considering various forces.
• Metabolomics profiles of fathead minnow epithelial cells exposed to MWNTs were compared.

Main Results:

• Surfactants required ultrasonication for MWNT dispersion; NOM enabled stable suspensions with both methods.
• MWNT suspensions were heterogeneous, with properties dependent on dispersant type/concentration, not preparation method.
• Aggregation and deposition were governed by van der Waals, electrostatic, and non-DLVO forces.
• Distinct metabolomics profiles were observed for SON/NOM-MWNTs and LT/NOM-MWNTs.

Conclusions:

• Dispersion method has minimal impact on MWNT physicochemical properties but influences biological interactions.
• NOM plays a crucial role in forming stable MWNT suspensions.
• Understanding dispersion effects is vital for assessing MWNT environmental risks and biological impacts.