Preparation And Bio-safe Assessing Of Several Nanomaterials Including Nano-ZnO, Nano-Mn₃O₄ And Ce-doped Nano-TiO₂

Nanotechnology revealed prodigious vitality in science interaction, and became a field with extensive scientific contents and potential applying prospect. Recently, a lot of researches had introduced nanotechnology into life science, and formed a dramatic world, in which based on nano structure and molecular recognition, disease diagnosing, therapy, targetable drugs delivery and control releasing could be implemented with nano-systems participating. Nano-materials can reach any position in living body theoretically for their ultrafine diameter, which is good or evil, depends on their safety. Then, nanotoxicity had been one of the most notable fields people focused on.Macro-size particles can enter into cells via internalization. However, for the ultrafine diameter, how do nano size particles go cross the cell membrane is still unknown. Furthermore, some investigations had claimed that nano-TiO₂ under UV irradiating could induce cancer cell apoptosis, but little verification had been given.In the present, Cerium element-doped nano TiO₂ (CDT), ZnO, and Mn₃O₄ nanostructures were prepared by wet chemical method. The way of nano-size CDT going cross the cell membrane was focused on, and its intrinsic mechanism was also discussed. Based on structural and optical properties of CDT, toxicology in vitro as well as in vivo, and phototherapy effect on cancer cell in vitro of CDT were investigated.Nano-size CDTs were prepared using impregnating method. The microstructure and morphology of the doped samples were characterized by using X-ray Diffraction (XRD), UV-vis diffractive reflectance spectrophotometer (UV-vis) and transmission electron microscopy (TEM). The results showed that as-prepared nano-size CDTs were about 20nm in diameter with anatase structure, cerium ions had entered the unit cell of nano-TiO₂, so the cell units had been swelled. Ce-doping enhanced photocatalysis by diminishing the band-gap of nano TiO₂, and the absorption edge of CDT was shifted to the long-wavelength region (named red shift),.Nano-size ZnO was fabricated by using microemulsion technique. Dropwise introducing hydrazine hydrate alcoholic solution into Zinc Acetate/xylene system, well dispersed wurtzite structure ZnO nanoparticles were prepared with about 5nm in diameter. With the same process, a 5nm Mn₃O₄ was also synthesized.With human hepatocellular line L02 cell, in vitro cytotoxicity of nana-size CDT, ZnO and Mn₃O₄ was checked. The results of MTT showed that CDT and Mn₃O₄ exposure didn't inhibit proliferation of L02. Lactate dehydrogenase (LDH) in test only slightly increased, however, had no significant difference to control ones. But nano ZnO had shown significant toxicity to huaman normal hepatocellular.TEM images indicated aggregations of CDTs were taken up into cells by endocytosis, and finally form an endocytic vesicle with membrane-bound. But to single CDT particle and clusters consisting of as few as two to three particle, which profiles were observed in both cytoplasm and in nucleus with no membrane bound, must went into cell by a non-endocytic way. CDT nanoparticle translocated in L02 cells, and induced apoptotic and necrotic cell death. Ultrastructure of cells changed, mitochondrias swelled, cristae of most mitochondrial became short or disappear, GER swelled and nucleus shrank in size, nuclear envelope deformed, and some area pullulated from nucleus, which are all evidence of apoptosis. The present study strongly supports the toxicity of nanoparticles in cells. At the same time, aggregation of CDTs in endocytic vesicle with membrane-bound didn't affect cell proliferation and mitotic division.With Bel7402 human hepatoma cell as a modal, we studied photokilling effect of CDT on tumor cells in present of UV light. Results showed that neither CDT nor low exposure time of UV light could inhibit cell proliferation. In the present of UV, Bel 7402 was killed at a higher speed, cells shrunk, bubbled, and lot of cell debris appeared after photocatalytic oxidation. DNA electrophoresis and Hoe fluorescence microscopes indicated that apart from cell necrotic disintegration, Bel7402 can also be induced apoptosis either in UV or in visible light, and cells were arrest in G2 phase.All of samples could increase lactate dehydrogenase (LDH) in blood, malondialdehyde (MDA) in Liver tissue, and decrease superoxide dismutase (SOD) in Liver in vivo. Of the total three, nano-size ZnO group changed significantly, and the other two groups had no significance relative to control ones, in general, variation of intraperitoneal injection exposure was larger than that of intragastric administration exposure. Nano-size ZnO could cause damage in organs.In intragastric administration exposure, portal area of liver enlarged and renal glomerulus swelled. In intraperitoneal injection exposure group, part of spleens necrosis and inflammatory cell infiltration had been checked.