Search

The aim of our investigation was to make a comparative assessment of the biological effects of silver nanoparticles encapsulated in a natural and synthetic polymer matrix. We carried out a comparative assessment of the biological effect of silver nanocomposites on natural (arabinogalactan) and synthetic (poly-1-vinyl-1,2,4-triazole) matrices. We used 144 three-month-old white outbred male rats, which were divided into six groups. Substances were administered orally for 9 days at a dose 500 μg/kg. Twelve rats from each group were withdrawn from the experiment immediately after nine days of exposure (early period), and the remaining 12 rats were withdrawn from the experiment 6 months after the end of the nine-day exposure (long-term period). We investigated the parietal-temporal area of the cerebral cortex using histological (morphological assessments of nervous tissue), electron microscopic (calculation of mitochondrial areas and assessment of the quality of the cell nucleus), and immunohistochemical methods (study of the expression of proteins regulating apoptosis bcl-2 and caspase 3). We found that the effect of the nanocomposite on the arabinogalactan matrix causes a disturbance in the nervous tissue structure, an increase in the area of mitochondria, a disturbance of the structure of nerve cells, and activation of the process of apoptosis.

The article presents results on experimental modelling an influence of silver nanoparticles incorporated into natural polymer arabinogalactane matrix on brain tissue of white outbred rats. The rats underwent parenteral injection of silver nanoparticles incorporated into polymer arabinogalactane matrix (dosage of 100 and 500 micrograms of silver per kg of the animal weight). The studies covered expression of 2 proteins participating in apoptosis process, in mitochondrial activation type - caspase-3 and protein bcl-2. During experiment, the groups examined demonstrated significant dose-dependent effect of bcl- 2 protein expression and increased number of caspase-3 expressed and non-expressed hyperchromic cells under exposure to argentumarabinogalactane - that indicates disorders of cellular structure and apoptosis development.

There are presented results of the immunohistochemical study of neural tissue of outbred albino rats exposed for 9 days to the influence of the silver nanobiocomposite consisted of silver nanoparticles encapsulated into a matrix of a natural polymer - arabinogalactan. The research of albino rats was performed in 2 stages: half of the rats in each groups were decapitated immediately after the exposure (early period) and the rest animals - 6 months after the end of exposure (remote period). The impact of the studied substance was proved to cause functional changes in cells of the nervous tissue. After the subacute administration of the nanobiocomposite - argentum-arabinogalactan (nano-Ag-AG) in cells of the nervous tissue of the brain of albino rats the expression of apoptotic and anti-apoptotic protein (caspase-3 and bcl-2) was established to be changed. The number of normal neurons producing protein caspase-3 sharply increases. Herewith the number of immunonegative neurons fairly declines. Along with this there is noted the high level of bcl-2 content, one function ofwhich is the preclusion ofapoptosis. In preparations there is revealed a significant gain in the number of bcl-2 expressing neurons, however, the protective effect of the protein is not fully realized, that leads to the significantly increase in the content of damaged hyperchromatic cells. The evaluation of results of the immunohistochemical study of the nervous tissue of albino rats according to data concerning the proteins caspase-3 and bcl-2 expression permits to make a conclusion about the capability of nanoargentum encapsulated into polymer matrix by passing the blood-brain barrier to induce the triggering apoptosis cascade in neurons of the cerebral cortex.

The article presents results of histologic and immunohistochemical examination of nerve tissue of outbred white rats subjected over 9 days to nanobiocomposite containing nanoparticles of silver and natural biopolymer arabinogalactane. Exposure to the studied chemical was proved to cause structural and functional changes in nervous tissue. Comparing results of structural study of nervous tissue with expression of proteins caspase-3 and bcl-2 proves ability of nanosilver incapsulated into polymer matrix to penetrate through blood-brain barrier and induce apoptosis in neurons of brain cortex.