Impact of in vitro digestion on gastrointestinal fate and uptake of silver nanoparticles with different surface modifications

Abstract

Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal in vitro model of differentiated Caco-2/HT29-MTX cells. The co-culture model was exposed to different concentrations (250-2500 mg/L) of pristine and in vitro digested (IVD) AgNPs and silver nitrate for 24 h. ICP-MS and spICP-MS measurements were performed for quantification of total Ag and AgNPs. The AgNPs size distribution, dissolution, and particle concentration (mass-and number-based) were characterized in the cell fraction and in the apical and basolateral compartments of the monolayer cultures. A significant fraction of the AgNPs dissolved (86-92% and 48-70%) during the digestion. Cellular exposure to increasing concentrations of pristine or IVD AgNPs resulted in a concentration dependent increase of total Ag and AgNPs content in the cellular fractions. The cellular concentrations were significantly lower following exposure to IVD AgNPs compared to the pristine AgNPs. Transport of silver as either total Ag or AgNPs was limited (<0.1%) following exposure to pristine and IVD AgNPs. We conclude that the surface chemistry of AgNPs and their digestion influence their dissolution properties, uptake/association with the Caco-2/HT29-MTX monolayer. This highlights the need to take in vitro digestion into account when studying nanoparticle toxicokinetics and toxicodynamics in cellular in vitro model systems.

Silver Nanoparticles against Foodborne Bacteria. Effects at Intestinal Level and Health Limitations

“…The toxicity difference between digested and undigested silver nanoparticles was also studied. It was possible to verify how the undigested ones were mostly captured by the cellular model Caco-2/HT29-MTX [88]. In the study of Silvan et al [33], exposure of GSH-Ag NPs to epithelial cells (HT-29, Caco-2 and CCD-18) showed a dose-dependent cytotoxic effect and no significant cytotoxicity occurred until concentrations of 4.93 µg/mL.…”

Combination of the BeWo b30 placental transport model and the embryonic stem cell test to assess the potential developmental toxicity of silver nanoparticles

“…Besides, the IC 50 values for cytotoxicity of the AgNPs in the mESCs were higher than what would be considered realistic in vivo concentrations as our results from the BeWo b30 transport experiments indicated low transport of AgNPs into the fetal compartment. Additionally, considering the oral route as one of the main exposure routes of the AgNPs, it is important to take into account also their very low transport across the intestinal barrier in vitro [14,56] and in vivo [15] which will consequently lower the concentrations of the AgNPs that might reach the fetus.…”

“…Previously, we studied the potential transport of AgNPs with different surface modifications across monolayers of intestinal epithelial cells in vitro [14]. We showed that in vitro simulated human digestion had a drastic effect on the dissolution of AgNPs, an effect that was surface coating dependent.…”

Dynamic in vitro intestinal barrier model coupled to chip-based liquid chromatography mass spectrometry for oral bioavailability studies

“…Caco-2 cells were used at passage numbers 29-40, and HT29-MTX-E12 cells were used at passage numbers 52-70 for all experiments. Cells were cultured in DMEM containing 10% FBS, 1% NEAA and 1% penicillin-streptomycin and maintained at 37°C in a 5% CO 2 -humidified air atmosphere and subcultured every 2 days to 3 days similar to the study of Abdelkhaliq et al [26]. For permeability experiments, cells were seeded at a density of 40,000 cells/cm 2 on a polycarbonate Transwell insert (area 0.6 cm 2 , 0.4 μm pore size; Millipore) as follows: Caco-2 and HT29-MTX-E12 cells were seeded in a 3:1 ratio on the apical side of the Transwell system and allowed to attach for 24 h. After 24 h, cell culture medium was refreshed every 2-3 days and Transwell systems were used for permeability experiments following 21 days of culturing.…”