Biological Studies on the Effect of Some Nano-Materials Used in Processing Military Protection Wears on the Skin

Abstract

Nanotechnology seems to have a productive prospect for the future due to the realization that the NPs possess properties that differ significantly from those observed in bulk materials. However, as the outcome of unique properties of NPs especially in the field of military protection wears, and because of increasing potential for exposure to them, there are growing concerns about the toxicity of zinc oxide, titanium dioxide and carbon black nanoparticles, as they helpfully provide many advantage applications in this field. Accordingly the present study was designed to evaluate the hazard of sphere ZnO, TiO2 and CB-NPs with mean particle size of 62, 25 and 20 nm, respectively, on rabbit's skin at the cellular and molecular levels. Three concentrations of aqueous suspensions of each NPs (0.5, 1.0 and 2.0 % w/v) were prepared and tested on the shaved skin with three exposure times (24, 48 and 72hrs) for each concentration. The histology, morphology, morphometry and ultrastructure of the skin were examined by the light and electron microscopy. In addition, to know to what extent such chemicals in the nanoform are harmful on the molecular level, esterase patterns, general proteins and glutathione system of the skin were studied The results suggested that ZnO, TiO2 and CB-NPs seem to have noxious effects on the skin. The findings of light and electron microscopy in the present study demonstrated the ability of these NPs to penetrate the skin and overcome the barrier function of the corneum layer. The penetration level was time and dose dependent. On the other hand, the Preface xxiii penetration of these NPs was accompanied with a series of alterations on the examined molecular parameters. Glutathione level, electrophoretic patterns of ESTs and general proteins were affected. In addition, the particle size seems to be an essential factor in the toxicity of the examined NPs. This finding was attained regarding to level of penetration (CB-NPs > TiO2-NPs > ZnO-NPs) with the subsequent ultrastructural deformity within the skin layers, as well as the gradual effects on the skin contents of glutathione, ESTs and general proteins. However, the results provide strong evidence that, the examined NPs could act as stressor and alter the normal homeostasis in the skin cells. This effect was attributed to ROS formation. The consequent inhibition of the antioxidant enzymes and detoxifying enzymes destroyed the balance between oxidation and anti-oxidation, which in turn led to a series of ultrastructural changes within the tissue and provoked the disturbances in the normal protein content. Among the morphological alterations; hyperkeratosis