RESUMO
Aqueous suspensions of 10 nm, 50 nm, or 1 µm Fe(3)O(4) particles were injected intraperitoneally (ip) to rats at a dose of 500 mg/kg in 4 mL of sterile deionized water 3 times a week for 5 weeks. Following exposure, functional and biochemical indices and histopathological examinations of spleen and liver tissues of exposed rats were evaluated for signs of toxicity. The iron content of the blood was measured photometrically, and that of the liver and the spleen by atomic adsorption spectroscopy (AAS) and electron paramagnetic resonance (EPR) methods. It was found that, given equal mass doses, Fe(3)O(4) nanoparticles possess considerably higher systemic toxicity than microparticles, but within the nanometric range the relationship between particle size and resorptive toxicity is intricate and nonunique. The latter fact may be attributed to differences in different nanoparticles' toxicokinetics, which are controlled by both more or less substantial direct penetration of nanoparticles through biological barriers and their unequal solubility.
Assuntos
Óxido Ferroso-Férrico/farmacocinética , Óxido Ferroso-Férrico/toxicidade , Nanopartículas Metálicas/toxicidade , Animais , Espectroscopia de Ressonância de Spin Eletrônica , Feminino , Injeções Intraperitoneais , Ferro/sangue , Fígado/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Tamanho da Partícula , Ratos , Espectrofotometria Atômica , Baço/química , Baço/efeitos dos fármacos , Baço/metabolismo , Testes de ToxicidadeRESUMO
We studied differences between phagocytic responses to nanoparticles (NPs) versus microparticles in the pulmonary region by synthesizing magnetite of different sizes and instilling suspensions of these particles intratracheally into rats' lungs. Ten and 50 nm particles caused a greater increase in cell counts of the bronchoalveolar lavage fluid (BALF) than the instillation of microparticles. The response to 10 nm particles was weaker than to 50 nm ones, and the smaller NPs were more cytotoxic; both were more cytotoxic than the microparticles. Phagocytic activity was also studied using optical and atomic force microscopy. Phagocytes were more "loaded" in the lungs instilled with 10 nm particles as compared with those instilled with 50 nm particles; NPs of both sizes were engulfed more avidly than microparticles. We found in a separate comparative experiment that magnetite NPs were more cytotoxic than titanium dioxide and quartz suspensions having particle size distribution typical of industrial dusts.