Detection of Gold Nanoparticles in Rat Organs by Transmission Electron Microscopy.

The effects of water-dispersed gold nanoparticles (8.0±0.9 nm in diameter) on the rat small intestinal mucosa and Peyer plaques, liver, and spleen were studied by electron microscopy. Water-dispersed gold nanoparticles injected into isolated intestinal loop not only accumulated in the small intestinal mucosa and Peyer plaques, but also penetrated into other organs, e.g. liver and spleen. Ultrastructural changes in the cells (hyperplasia of endoplasmic reticulum) were detected in the studied organs.

[Toxicological evaluation of nanosized colloidal silver, stabilized with polyvinylpyrrolidone. I. Characterization of nanomaterial, integral, hematological parameters, level of thiol compounds and liver cell apoptosis].

Nano-sized colloidal silver (NCS) is currently one of the most widely used nanomaterials in medicine and consumer's products. Nanoparticles (NPs) of silver, in addition to the direct exposition through products may expose human via various environmental objects. The aim of the study is to assess the safe doses of silver NP received orally. The investigated NCS contained silver NPs with diameter of 10­60 nm, predominantly with a nearly spherical form stabilized with polyvinylpyrrolidone (PVP). The experiment was performed during 92 days in 5 groups of male Wistar rats (n=15 in each group), receiving a balanced semisynthetic diet. Animal of group 1 (control) received vehicle (deionized water) intragastrically for 30 days and then with food, groups from 2nd to 4th ­ PVP and groups from 3rd to 5th NCS, in doses respectively, 0.1; 1.0 and 10 mg/kg body weight (b.w.) in terms of silver. The dose of PVP in groups from 2nd to 5th did not differ, amounting to 200 mg/kg b.w. During the experiment, the weight gain, skin condition, activity, stool, cognitive function were assessed. At the end of the feeding period weight of internal organs, intestinal wall permeability to protein macromolecules, liver thiols, standard values of blood erythrocytes, leukocytes and platelets, hepatocyte apoptosis by flow cytometry were studied. These results suggest that in terms of weight gain, lung relative mass, average erythrocyte volume, hemoglobin content and concentration in erythrocytes, the relative proportion of lymphocytes and neutrophils adverse changes have been observed at a dose of 10 mg NPs per kg of b.w. At lower levels of exposure (0.1 and 1.0 mg/kg b.w.) some specific changes were also observed (in terms of thiols pool in liver, cognitive function, relative abundance of monocytes, the number of dead hepatocytes), which, however, did not possess an unambiguous dependence on the dose. Possible mechanisms of the toxic action of the NCS have been discussed.

Identification of silver nanoparticles in the small intestinal mucosa, liver, and spleen of rats by transmission electron microscopy.

The effects of water-dispersed Ag nanoparticles on the small intestinal mucosa, liver, and spleen of rats were studied by transmission electron microscopy. Acute experiments demonstrated penetration of Ag nanoparticles injected into the isolated intestinal loop into the intestinal mucosa, liver, and splenic tissues. Ultrastructural changes (lobed nucleus, megamitochondria) were found in the studied organs. These data indicated that injection of water-dispersed Ag nanoparticles into the gastrointestinal tract was followed by their penetration through the epithelium of the small intestinal mucosa into other organs, e.g. into the liver and spleen. This fact is essential for evaluation of potential risks of the nanoparticle effects on human health and environment.

[Characterization of silver nanoparticles migration from package materials destined for contact with foods].

There was studied migration of artificial silver nanoparticles from polyethylene films destined for package of such foods as bread and poultry into model media reproducing physico-chemical properties and composition of said products. Modification of films was performed by 5- or 10-fold spraying of silver nanoparticles on the surface of package material. Model media were composed from water, alcohol and plant oil according to US FDA and Russian Federal Service for Surveillance of Consumer Rights Protection and Human Well-Being official recommendation. Nanoparticles were detected in model media by means of transmission electron and atomic force microscopy. Quantification of silver in nanoparticles migrating from films was performed by mass-spectrometry with inductively coupled plasma. The results obtained showed that silver migrated from films into test media in form of nanoparticles with mean diameter close to 10-20 nm. Migrated particles were partially aggregated to complexes with dimension about 50 nm with degree of aggregation depending on media composition. Quantification showed that amounts of silver nanoparticles migrating in foods did not exceed save level of this nanomaterial consumption even in aggravated conditions when almost all volume of product was consumed in form packaged in films modified with nanosilver.

[Role of L-phenylalanine ammonia lyase in the induced resistance and susceptibility of potato plants].

Biogenic elicitors (chitosan and its complex with salicylic acid) and an immunosuppressor (laminarin) were shown to increase the activity of L-phenylalanine ammonia lyase (EC 4.3.1.5) and protein synthesis in potato tubers. Laminarin did not decrease L-phenylalanine ammonia lyase activity. It is unlikely that the activity of this enzyme may serve as a criterion for the induced resistance.