Comparative Study On Cytotoxic Characteristics Caused By Three Kinds Nano-scale Materials And Non-nano Materials

When the material dimension achieves to nano-scale, the physicochemical properties would be changed significantly. Whereas the biological effect of xenobiotic is direct correlation with the physicochemical properties. It is probably that the biological effect is greatly different between nano-scale and non-nano materials in organism. Whether the present chemical safety evaluation mode and method could be suit for nano-scale materials? How to answer this question has become research focus. The cells which choose in this study are portal of entry for lungs, skin, and the mucosal membrane,including human bronchial epithelial cell line (BEAS-2B),human keratinocyte cell line(HaCaT),human epithelial colorectal adenocarcinoma cells (Caco-2) and human monocytic cell line (THP-1), common immune system target cell. Compare the cytotoxicity and cytotoxic characteristics caused by three kinds nano-scale materials ( Titanium Dioxide, TiO₂. Single-wall carbon nanometer tube, SWNCT. Polystyrene ) and corresponding non-nano materials ( Titanium Dioxide TiO₂, Carbon black, Polystyrene) and study whether fluorescence labeling influence the cytotoxic characteristics of nano-scale polystyrene and cell distribution. The objective of this study is to reveal nanomaterials toxic characteristics and explore the feasibility that fluorescent labeling nano-scale materials apply to study cell kinetics, so provide the evidence for determined nano-scale materials safety evaluation.The research results are: 1)There was no significant influence on the time of nano-scale polystyrene entrying the cell and distribution in cell by fluorescence labeling, no significant influence for cytotoxicity and cytotoxic characteristics of nano-scale polystyrene caused by fluorescence labeling.2)The cytotoxic effects of three nano-scale materials were greater than non-nano materials. There is size-toxicity relation for nano-scale TiO₂. The cytotoxic effects were increasing following with dimensional diminished: TiO₂(<25nm )>TiO₂(<75nm) > TiO₂( < 100nm) > TiO₂(non-nano). There is significant dose-effect relationship, time-effect relationship on nanomaterials toxic characteristics. And the toxic effects occurred earlier for time and lower for dose compared with non-nano materials. On toxic properties,TiO₂(<25nm) can induce BEAS-2B cell and THP-1 cell apoptosis comparing with non-nano TiO₂ . TiO₂ (<25nm) could induce THP-1 cytotoxicity such as subcellular organelle vacuolization, nuclear pyknosis, and nucleoplasm agglutination , which could not be tested by non-nano TiO₂.3)There was difference cytotoxic among four cells by the same material. Compared with Caco-2 and HaCaT cells, the cytotoxic effects of three kinds nano-scale materials to BEAS-2B and THP-1 cells were more sensitive. The toxicity sequence of above nano and non-nano TiO₂, SWNCT and carbon black, micron polystyrene and nano polystyrene to three kinds portal of entry cells were BEAS-2B>Caco-2>HaCaT, It was same for toxicity of three kinds exposure routes on confirmed animal experiment of non-nano and nano materials above. The three kinds portal of entry cells in vitro could reflect partly the sensitive of the same material to different exposure routes, it may be benefical to select or determine the exposure routes on animal experiments.4)In the mouse lymphoma cell micronuclei test to detect SWCNT, The micronuclear rate in groups had statistic variance since SWCNT exceed 80μg/ml on 24 hour and exceed 40μg/ml on 48 hour. The micronuclear rate was fairly exceeding 3 times to the negative control in high dose group. In the mouse lymphoma cell Tk gene mutation to detect the SWCNT, and the mutation frequence of positive control (4-NQO and CP)exceed 2 times to the solvent control( normal saline), RTG(%) was in 10%～20% on high dose group, there was no significant difference on mutation frequence between SWNCT group and solvent control, the Tk gene mutation is negative.This research work suggest that the fluorescent labeling nano-scale polystyrene can be applid to study cell kinetics and toxicokinetics in vivo equal to the same size polystyrene. The time and the dose which nanomaterials induced cytotoxicity is less than micro-scale materials.There is significantly different between TiO₂(<25nm) and TiO₂ (non-nano) on toxic properties,TiO₂(<25nm) can induce apoptosis and nuclear damage. The cell toxicity of three kinds portal of entry cells could reflect partly the sensitiveness of the same material to different exposure routes on body. SWNCT can lead to injury of chromosome, but do not cause cell gene mutation .