Behaviour of silver nanoparticles and silver ions in an in vitro human gastrointestinal digestion model

Abstract

Oral ingestion is an important exposure route for silver nanoparticles (AgNPs), but their fate during gastrointestinal digestion is unknown. This was studied for 60 nm AgNPs and silver ions (AgNO₃) using in vitro human digestion model. Samples after saliva, gastric and intestinal digestion were analysed with SP-ICPMS, DLS and SEM-EDX. In presence of proteins, after gastric digestion the number of particles dropped significantly, to rise back to original values after the intestinal digestion. SEM-EDX revealed that reduction in number of particles was caused by their clustering. These clusters were composed of AgNPs and chlorine. During intestinal digestion, these clusters disintegrated back into single 60 nm AgNPs. The authors conclude that these AgNPs under physiological conditions can reach the intestinal wall in their initial size and composition. Importantly, intestinal digestion of AgNO₃ in presence of proteins resulted in particle formation. These nanoparticles (of 20-30 nm) were composed of silver, sulphur and chlorine.

Nanomaterialien in Lebensmitteln – toxikologische Eigenschaften und Risikobewertung

“…Je nach individueller physikochemischer Natur des betrachteten Nanopartikels kann infolge der chemischen Umgebung des Magen-Darm-Trakts unterUmständen eine vollständige Auflösung anorganischer Nanopartikel oder eine Aggregation zu größeren Partikeln erfolgen [27][28][29]. Umgekehrt konnte gleichzeitig eine Neubildung von nanoskaligen Strukturen aus gelösten Verbindungen im Magen-Darm-Trakt gezeigt werden [30]. Die Verdauungssäfte enthalten zudem unterschiedliche Enzyme wie Glycosidasen, Proteinasen und Lipasen, die insbesondere zu Veränderungen von organischenNanopartikelnführenkönnen.…”

“…Stattdessen kommen zum Studium dieser Phänomene zumeist artifizielle Modelle des Verdauungstrakts zur Anwendung, welche die verschiedenen Abschnitte der gastrointestinalen Passage und ihre chemischen Gegebenheiten, wie etwa den Speichel in der Mundhöhle, den Magensaft oder die intestinale Flüs-sigkeit, nachstellen. Dies ermöglicht eine Untersuchung der Partikeleigenschaften entlang der Teilschritte der Verdauung auch unter der Berücksichtigung der gleichzeitigen Präsenz verschiedener Nahrungsmittelbestandteile [27,28,30,32,33]. In diesem Zusammenhang wird diskutiert und untersucht, inwieweit Nanopartikel aufgrund ihrer geringen Grö-ße möglicherweise bevorzugt physiologische Barrieren überwinden und somit in Zellen oder Gewebe aufgenommen werden können.…”

Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

“…Although DLS has serious limitations for sizing nanoparticle suspensions in complex matrices, it is very valuable to monitor aggregation behaviours. For example, aggregation of Ag NPs exposed to human synthetic stomach fluid [103], gastric juices [104] or river water [105] has been studied by DLS. In addition, this technique has also been used to proof the reliability of AF4 data in consumer products, although some results were biased to larger particle diameters respect to AF4 results [106].…”

“…SP-ICP-MS in combination with alkaline or enzymatic digestions has proven to provide reliable information about size distributions and number concentrations in laboratory studies involving food matrices spiked with silver or gold nanoparticles [32, 38, 40, 41], in tissues from organisms exposed to nanoparticles [33,37,42,124], and native nanoparticles in foods and consumer products [95]. SP-ICP-MS has also been applied to study the fate of silver nanoparticles in in vitro human digestion [104], lake mesocosms [50] and washing solutions from commercial detergents [90], to track their dissolution [127] and agglomeration [128] in natural waters or their release from food additives [129]. [142,143] and ZnO and CuO [144], and for speciation of silver in waters and soils from microcosm [145] and mesocosms [146] experiments.…”

Utility of models of the gastrointestinal tract for assessment of the digestion and absorption of engineered nanomaterials released from food matrices

“…The digestion of macronutrients has been validated with these models (Kopf-Bolanz et al, 2012), and the models have been applied to study the digestion of NMs by coupling the output material with robust analytical methods appropriate for complex matrices. For example, the fate of silver NMs was evaluated (Bohmert et al, 2013;Walczak et al, 2013). It appears that the presence of proteins and other food components has a crucial impact on the particle size kinetics during the different phases of digestion.…”