The safety of nanomaterials and nanotechnologies is an important factor in the regulation of industrial production and the introduction of nanoproducts into practice. The toxicological aspect of the use of silver nanoparticles (SNP) is insufficiently studied, leaving many questions without answer. The problem of dependence of toxicity on the shape and the size of nanoparticles is controversial and not well-studied, and there is a lack of research on the nanosilver effect on human and animal organisms.
Objective. The aim of the work was to provide the hygienic assessment of harmful effects of silver nanoparticles of spherical and decahedron shape.
Materials and Methods. Samples of solutions of spherical and decahedron SNP, synthesized by the method of photostimulated restoration, were intraperitoneally administered to white nonlinear rats both males and females aged 4 months. For the subacute toxicity study of spherical 45-nm nanosilver the animals were subdivided into three groups of (16 rats in each, 8 animals in a subgroup — according to gender). Every day they were injected with spherical SNP at doses of 0.1,1 and 5 mg/kg intraperitoneally for 14 days. The fourth group was the biological control. For the subacute toxicity study of decahedron 45-nm nanosilver the animals were subdivided into four groups (16 rats in each, 8 animals in the subgroup according to gender). The animals were injected intraperitoneally with 10, 5,1, and 0.1 mg/kg doses of SNP daily for 14 days. Fifth group was biological control. On 14th day animals were withdrawn from the experiment by decapitation under a slight, ethereal athetic.
Results and Discussion. It was grounded the expediency of taking into account the physical and chemical properties of silver nanoparticles, including geometrical characteristics (shape, specific area of surface), the number of silver ions in nanoparticle and the quantity of nanoparticles in the solution while the determination of exposition of nanosilver or other nanochemicals of different geometric shapes. On models of subacute effect there were determined the peculiarities of different shapes nanosilver exposure and hygienic meaning of biochemical and pathomorphological changes as criteria of harmful effect. With the help of morphometric analysis of pathomorphological changes of internal organs of rats there was ascertained doserelated harmful effect of decahedron and spherical silver nanoparticles. As a result of the experiment, dose-dependent circulating swelling of the epithelium of convoluted tubules of the kidneys, hepatocytes, nuclei of cardiomyocytes, alteration of the epithelium of bronchi of different caliber, repletion of the blood vessels of the walls of the respiratory parts of the lungs, karyopicnosis of neurons of the cerebral cortex were observed. The revealed changes in the indices of prooxidant-antioxidant equilibrium, some biochemical indices and the changes in internal organs of animals testified to the less toxic effect of silver nanospheres in comparison with silver nanodecahedrons.
Conclusions. 1. According to the analysis of the geometric characteristics of decahedron silver nanoparticles, it is established that the specific area of decaheders is 2 times bigger than the specific area of the spherical SNP, which provides twice bigger area of the contact of silver nanodecahedron in the biological environment. The decahedron nanoparticle contains 4.3 times less atoms than spherical, and, at the same mass concentration, a solution of nanosilver contains 4 times more silver nano decahedrons than spheres.
2. With the help of biochemical analyses of blood and liver tissue, as well as the morphometric analysis of pathological changes in the internal organs of laboratory rats, the dose-dependent harmful effect of silver nanoparticles of decahedral and, partially, spherical shape was established. The revealed changes in the blood and internal organs of animals testified to a less toxic effect of silver nanospheres in comparison with silver nanodecahedrons.
3. It was established that the differences in biochemical and pathomorphological changes in the internal organs of laboratory animals at the same dose of SNP the decahedron and spherical shape, calculated in mg/kg body weight, are related to a 4-multiple dose difference expressed in the ratio of «the number of nanoparticles/kg» of body weight and a 9-multiple difference in favor of nanodecahedrons while calculating the dose «specific surface area/kg» of body weight.
Key Words: silver nanoparticles, silver nanodecahedron, silver nanosphere, toxicity, nanosilver.
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