石墨烯对植物的毒性效应及机制研究

发布时间：2018-03-16 18:24

本文选题：石墨烯　切入点：斜生栅藻　出处：《浙江工商大学》2015年硕士论文　论文类型：学位论文

【摘要】：石墨烯作为一种新兴的二维碳纳米颗粒,因其优良的性能在能源存储、纳米电子设备、电池、透明导体和环境保护等方面有着广泛应用。随着石墨烯材料的大量使用,它们最终可能被释放到水、陆地和大气环境中。然而,石墨烯的生态风险和毒性机制目前尚未明确。本文以石墨烯作为研究对象,探究其对斜生栅藻(Scenedesmus obliquus)和小麦(Triticum aestivum L.)的毒性效应及内在机制,以期为今后石墨烯的生态效应研究提供理论依据。主要内容包括以下几部分：(1)不同石墨烯浓度0、10、20、50、100、150、200、250和300 mg L-1对斜生栅藻的生长影响表明,72 h后石墨烯能显著抑制斜生栅藻的生长,抑制现象呈浓度、时间效应。经Logistic和Gompertz模型计算ICso值分别为148和151 mg L-1。扫描和透射电镜分析石墨烯对藻细胞胞外和胞内显微形态影响结果表明,150 mg L-1石墨烯处理下藻细胞表面包裹一层薄膜；与对照相比,石墨烯处理后藻细胞的细胞壁呈破损现象；胞内两个明显的生理变化为染色质高度浓缩及细胞内淀粉粒增多。上述现象表明,石墨烯引起的胞外覆盖和胞内损伤可能是影响藻细胞生长的重要原因。此外,本研究还发现藻细胞的细胞膜通透性随石墨烯浓度升高而增大,表明藻细胞膜的完整性遭到破坏。通过测定藻细胞体内活性氧自由基(ROS)和丙二醛(MDA)含量发现,它们均随石墨烯浓度的升高而增加,说明藻细胞受到显著的氧化胁迫。另外,石墨烯还显著抑制了叶绿素a、叶绿素b及叶绿素a/b水平,暗示着光合作用受损。叶绿素荧光各参数分析结果表明,石墨烯处理后藻细胞光合系统Ⅱ(PSⅡ)实际量子产量Y(Ⅱ)、光化学淬灭系数qP、非光化学淬灭系数NPQ和相对光合电子传递速率rERT与对照组相比均降低,说明PSⅡ活性受损。由此,本研究认为石墨烯对藻细胞的毒性效应主要表现为胞外表面覆盖和胞内氧化损伤、光合作用受损,最终影响藻细胞的生长。(2)48 h短期石墨烯处理下小麦根系生长结果表明,250、500、1000和1500 mg L-1石墨烯处理与对照相比根系伸长率分别增加了69%、221%、208%和288%,说明石墨烯对小麦根系的生长有一定的促进。显微观察发现这可能与处理后细胞拉伸有关。此外,石墨烯处理下小麦根系出现了以下变化：根毛短而稀疏；根内MDA含量高；硝基四唑氮蓝和伊文思蓝染色增强；超氧化物歧化酶(SOD)和过氧化物酶(POD)活性随石墨烯浓度的升高先激活后抑制。上述现象均说明石墨烯处理后根系抗氧化系统受损。因此,石墨烯对小麦的短期毒性效应主要表现为根系的氧化胁迫及根毛发育迟缓。(3)30 d石墨烯处理下小麦生长结果表明,500 mg L-1石墨烯处理中小麦地上部生物量显著下降,叶片叶绿素含量降低,说明石墨烯长期处理可抑制小麦的生长。为研究石墨烯对小麦体内养分含量的影响,本研究首先分析了大量元素氮、磷和钾的情况。结果表明,石墨烯处理后叶片总氮、总钾含量下降,总磷含量基本保持不变。此外,石墨烯处理后叶片的中量元素如钙和镁含量也呈下降现象,而钠含量基本保持不变。石墨烯处理中小麦叶片的微量元素如锌、铁和铜含量降低,锰含量升高。上述数据说明,石墨烯长期处理后小麦体内大部分养分均受到了一定程度的抑制。因此,石墨烯对植物的养分代谢影响也是其毒性效应的重要表征。
[Abstract]:Graphene as a new two-dimensional carbon nano particles, because of its excellent performance in energy storage, nano electronic devices, batteries, have been widely applied in transparent conductors and environmental protection. With the extensive use of graphene materials, they may eventually be released into the water, land and air. However, graphite by the ecological risk and toxicity mechanism is not yet clear. This paper takes Shi Moxi as the research object, research on Scenedesmus (Scenedesmus obliquus) and wheat (Triticum aestivum L.) the toxic effects and mechanism, so as to provide theoretical basis for future research on the ecological effects of graphene. The main contents include the following parts: (1) showed that the effect of different concentrations of 0,10,20,50100150200250 graphene and 300 mg L-1 on the growth of Scenedesmus, after 72 h of graphene can significantly inhibit the growth of Scenedesmus obliquus, inhibit the phenomenon of dark Of the time effect. The results of Logistic and Gompertz model to calculate the ICso values were 148 and 151 mg L-1. scanning electron microscope and transmission electron microscope analysis results the morphology of graphene on cell extracellular and intracellular showed that 150 mg L-1 graphene under the treatment of the algal cell surface covered with a layer of thin film; compared with the control group, after treatment of graphene the cell wall of algal cells were damaged; two obvious physiological changes in intracellular for highly condensed chromatin and starch in cells increased. The phenomenon shows that the influence of growth of algae is an important reason why graphene may damage caused by extracellular and intracellular coverage. In addition, the study also found that the permeability of cell membrane algal cells increased with the concentration of graphene increases, integrity that algae cell membrane destruction. Through the determination of algal cells in vivo activity of oxygen free radicals (ROS) and malondialdehyde (MDA) content, they are with the concentration of graphene The increase that algal cells by oxidative stress significantly. In addition, graphene also inhibited the chlorophyll a, chlorophyll b and chlorophyll a/b levels, suggesting that photosynthesis is damaged. The parameters of chlorophyll fluorescence analysis results show that the graphene processed algal photosynthetic system II (PS II) the actual quantum yield (Y II), photochemical quenching coefficient qP, non photochemical quenching coefficient NPQ and the relative photosynthetic electron transport rate of rERT was lower compared with control group, indicating the damage of PS II activity. Thus, this study suggests that the toxic effect of graphene on cell mainly oxidative damage, extracellular and intracellular photosynthesis damaged surface coverage finally, affect the growth of algal cells. (2) 48 h short graphene under the treatment of root growth of wheat. The results showed that 2505001000 mg and 1500 L-1 graphene on photographic processing and root elongation were increased by 69%, 221%, 208% And 288%, that the growth of graphene on wheat root has certain promotion. This may be associated with the microscopic observation results showed that the cells treated with tension. In addition, graphene treatment appeared the following changes: wheat root hairs short and sparse; the content of MDA in the roots; four nitro tetrazolium and Evans blue staining enhancement; superoxide dismutase (SOD) and peroxidase (POD) activity increased with the concentration of graphene activation inhibition. This phenomenon showed impaired antioxidant system root of graphene after treatment. Therefore, the short-term toxicity of Shi Moxi wheat mainly manifested as root oxidative stress and root hair growth retardation (3) 30. D graphene under the treatment of wheat growth. The results showed that 500 mg L-1 graphene processing biomass and wheat decreased significantly, chlorophyll content decreased, indicating graphene long-term treatment could inhibit the growth of wheat for research. The effect of graphene on nutrient content in wheat, this study first analyzed the nitrogen, phosphorus and potassium. The results show that the graphene processed leaf total nitrogen, total potassium content decreased, total phosphorus content remained unchanged. In addition, graphene treated leaf elements such as calcium and magnesium content in a declining phenomenon, and the sodium content remained unchanged. The graphene processing of wheat leaf trace elements such as zinc, iron and copper content decreased, manganese content increased. The above data shows that graphene long-term treatment most of the nutrient in wheat was inhibited to a certain extent. Therefore, the important effect of characterization of graphene nutrient metabolism the plant is also its toxic effects.

【学位授予单位】：浙江工商大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X171.5;TQ127.11

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