Dissolution Behavior and Biodurability of Ingested Engineered Nanomaterials in the Gastrointestinal Environment

Area of Science:

• Environmental Science & Engineering
• Materials Science
• Toxicology

Background:

• Engineered nanomaterials (ENM) are increasingly used as food additives.
• The fate and behavior of ingested ENM (iENM) within the gastrointestinal (GI) environment remain largely unknown.
• Understanding iENM behavior is crucial for assessing potential human health risks.

Purpose of the Study:

• To investigate the dissolution, biodurability, and persistence of major iENM in simulated GI fluids.
• To evaluate iENM behavior across a physiologically relevant digestion cascade (saliva → gastric → intestinal).
• To establish a biodurability ranking of common iENM under simulated GI conditions.

Main Methods:

• Simulated digestion experiments using individual GI fluids (saliva, gastric, intestinal) and a cascade model.
• Analysis of four major iENM: titanium dioxide (TiO2), silicon dioxide (SiO2), zinc oxide (ZnO), and two iron oxides (Fe2O3).
• Utilized high-resolution particle analysis, electron microscopy, and time-dependent dissolution measurements.

Main Results:

• TiO2 exhibited the highest biodurability and persistence, with minimal ion release (<0.42%).
• Iron oxides showed moderate persistence, with rod-like morphology being more stable than acicular.
• SiO2 and ZnO demonstrated lower biodurability, with complete dissolution of ZnO and significant SiO2 dissolution in the gastric phase; SiO2 reprecipitated in the intestinal phase.

Conclusions:

• The biodurability ranking in simulated GI conditions is: TiO2 ≫ rod-like Fe2O3 > acicular Fe2O3 ≫ SiO2 > ZnO.
• Observed behaviors align with limited animal biokinetics data, suggesting potential for chronic uptake.
• Further research is essential to understand the health implications of chronic iENM exposure, considering food matrices and authentic digestive media.