Transformations of Ag2S nanoparticles in simulated human gastrointestinal tract: Impacts of the degree and origin of sulfidation

Abstract Engineered silver sulfide nanoparticles (e-Ag2S-NPs) are used in industry and can be released into the environment. Besides e-Ag2S-NPs, transformed silver sulfide nanoparticles (t-Ag2S-NPs) from silver nanoparticles are more likely to be the form that is widely distributed in the environment. Both e-Ag2S-NPs and t-Ag2S-NPs may be ingested and get into human gastrointestinal tract (GIT) through trophic transfer, posing a potential threat to human health. Nevertheless, knowledge of chemical stability of t-Ag2S-NPs and e-Ag2S-NPs in the human GIT is very limited. Herein e-Ag2S-NPs and a series of t-Ag2S-NPs with different degrees of sulfidation were selected as models for exposure to the simulated human GIT including mouth, stomach and small intestine phases under fed and fasted conditions. Silver ions were detected in the simulated saliva, gastric and small intestine fluids when t-Ag2S-NPs or e-Ag2S-NPs were incubated in the simulated GIT, but the amount (e.g.,