Avaliação dos parâmetros funcionais e estruturais renais de ratos tratados com biocompósitos baseados em nanotubos de carbono

Abstract

Toxicological studies involving possible effects of biocomposites based or not on carbon nanotubes (CNT) in biological systems are crucial to establish the safety of these materials. The objective of this present study was to evaluate potential damage in the function and structure of kidneys of rats whose tooth sockets were treated or not with biocomposites based on CNT. Samples of sodium hyaluronate (HY), single-walled CNT (SWCNT), SWCNT associated with HY (SWCNT-HY), multi-walled CNT (MWCNT) and MWCNT associated with HY (MWCNT-HY) were irradiated with doses of Gamma radiation from 100g to 30kg in order to define the optimal regimen of sterilization, which was established based on microbiological tests. Then, sterilized biomaterials were evaluated structurally by scanning electron microscopy and functionally through their effects on bone repair of tooth sockets. To assess the renal function and structure, the biocomposites were administered into tooth sockets (1% HY and 100g/mL CNT in 0.1mL) and after 7 days, the animals were placed in metabolic cages for urine collection and to measure the water intake and urine volume. Afterward, the rats were euthanized and blood and tissues (kidney and jaw) samples were collected. To evidence any potential toxic effects of these biocomposites, this protocol was repeated injecting the biomaterials intraperitoneally at higher concentration (0.75 mg/kg). The results demonstrated that doses of 250g and 2,5kg were sufficient to sterilize the HY and biocomposites based on CNT, respectively, without causing significant changes in their structure and biological activity. Analysis of renal function showed a significant increase in the concentration of plasma creatinine in the HY, SWCNT-HY and MWCNT-HY groups with consequent increases in the glomerular filtration rate. Regarding the free water excretion fraction, we observed a significant increase in the SWCNT group. Furthermore, microalbuminuria analysis revealed a significant decrease in this parameter in the MWCNT-HY group compared with control and MWCNT groups. Histologically, there were no significant changes in the glomerular structure. Concerning the intraperitoneal administration of these biomaterials, similar results were observed. We concluded that, when these biocomposites were used in tooth sockets at the proposed dosages, they were not able to induce functional or structural renal damage. Therefore, these results expand the perspectives of CNT applicability, as they showed no signs of toxicity.