Safety Evaluation of Nanosilver Using Reconstructed Human GIT Tissues

Silver nanoparticles (AgNPs) have been used widely in food storage materials and cosmetics for their well known antimicrobial effects. Information on the toxicity have not been sufficiently evaluated, although there is a risk of accidental ingestion or misuse. Recent studies revealed that silver nanoparticles may penetrate into the circulation system through the mucosa of the respiratory tract, gastrointestinal tract and by penetration through the skin. Penetration of nano-silver may lead to interactions with plasma proteins, coagulation factors, erythrocytes, white blood cells and thrombocytes. Oral ingestion of colloidal silver can increase the concentration of silver in the plasma and save the silver particles in the skin, which is later reflected by irreversible hyperpigmentation (argyria). According to previous studies in vitro, silver nanoparticles may be cytotoxic for hepatocytes and may cause oxidative stress, DNA damage and apoptosis. For safety evaluation of nanosilver, reconstructed human GIT tissues EpiOral, EpiIntestinal, EpiIntestinalFT and Colon epithelium were used as a model mimicking the human gastrointestinal tract. Biological methods in vitro were applied for evaluating the viability, cytotoxicity and penetration in tissue cultures. MTT viability assay was employed for evaluating the cytotoxicity and viability of the tissues. ICP-MS and TEM was used for detecting the penetration of AgNPs. ELISA method was used for investigation of inflammatory reactions. The results confirmed negative effect of nano-silver on viability of the tissues and neither cytotoxicity effect was revealed. Evaluating the penetration of nano-silver through the tissue, ICP-MS method confirmed the presence of nano-silver in the medium after exposure time of 24h of the Epi Intestinal FT tissue and Colon epithelium tissue. The results confirmed no adverse effect of nanosilver on the viability of the tissues even after exaggerated exposure. Penetration of nanosilver through the tissues, probably in the form of Ag ions, was confirmed by ICP-MS in a rate depending on the tissue type and application vehicle. No significant (at least two-fold) increase of the inflammatory cytokines was recorded by ELISA method. The tested AgNP samples did not elicit any adverse effects in the available reconstructed human GIT tissues.

EpiIntestinal (SMI-100), SMI-100-FT, IL-1a, TNF-1, IL-6, IL-8, MTT tissue viability, GIT tissues, inflammation, nanosilver, penetration

Silver nanoparticles (AgNPs)