Transformation and Speciation Analysis of Silver Nanoparticles of Dietary Supplement in Simulated Human Gastrointestinal Tract

Abstract

Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.

Transformation of Nanomaterials and Its Implications in Gut Nanotoxicology

“…The authors observed no aggregation of the Ag NPs or dissolution in the simulated saliva containing mucin and α‐amylase, and attributed this stabilization to the biomolecular corona formation on the NP surface. [ 101 ] In good agreement, minimal aggregation and dissolution of Ag NPs was reported in authentic saliva, a phenomenon the authors of the study attributed to macromolecular corona formation on the Ag NPs surface. [ 102 ] In the gastric phase, extensive oxidative dissolution of Ag NPs (≈72 wt% of total Ag NPs) was observed due to the high acidity and Cl − concentration, which was noted to be slowed down in the presence of mucin.…”

“…The structural and physicochemical properties of commercial Ag ENMs, specifically their interfacial properties, could be expected to differ from those of laboratory‐synthesized AgNPs, and might contribute to contrasting transformation outcomes. In a recent study, Wu et al [ 101 ] subjected a realistic concentration of commercial Ag NPs based dietary supplement to a sequential cascade of salivary, gastric, and intestinal fluid treatment, to understand their transformation in GIT. The authors observed no aggregation of the Ag NPs or dissolution in the simulated saliva containing mucin and α‐amylase, and attributed this stabilization to the biomolecular corona formation on the NP surface.…”

“…[ 102 ] In the gastric phase, extensive oxidative dissolution of Ag NPs (≈72 wt% of total Ag NPs) was observed due to the high acidity and Cl − concentration, which was noted to be slowed down in the presence of mucin. Speciation analysis revealed the vast majority of these released Ag + ions formed Ag‐biomolecules complexes, presumably with mucin and other digestive enzymes; [ 101 ] while AgCl precipitates made up the rest of the resulting species. [ 101,103 ] No further dissolution and aggregation of Ag NPs were detected in the small intestine phase, with close to 20 wt% of the Ag NPs retaining their nano‐size form.…”

“…Speciation analysis revealed the vast majority of these released Ag + ions formed Ag‐biomolecules complexes, presumably with mucin and other digestive enzymes; [ 101 ] while AgCl precipitates made up the rest of the resulting species. [ 101,103 ] No further dissolution and aggregation of Ag NPs were detected in the small intestine phase, with close to 20 wt% of the Ag NPs retaining their nano‐size form. Ag‐biomolecule complexes made up the bulk of the detected species in the small intestine microenvironment.…”

“…Ag‐biomolecule complexes made up the bulk of the detected species in the small intestine microenvironment. [ 101 ]…”