【作者】 滕红霞；

【导师】 刘宪华；

【作者基本信息】 天津大学 ， 环境科学， 2009， 硕士

【摘要】 随着人们对环境质量要求的提高,发展高灵敏的、对环境污染物有特异性响应的检测技术对国民健康和经济发展具有重要意义。将纳米材料引入化学传感器是分析化学的一个研究热点,其中氧化锌纳米材料因其独特的力学、电子特性及化学稳定性,得到了广泛关注。纳米结构的制备方法有多种,用生物模板组装纳米结构具有高效、廉价的特点,因而受到了极大的关注。DNA可以吸附金属离子,而且形状可以根据需要进行设计,是一种最常用的生物模板。在本文中,使用生物大分子DNA做模板,硝酸锌做反应原料,分别采用一乙醇胺(MEA)和六次甲基四胺(HMT)做还原剂,在水浴加热的条件下制备了氧化锌纳米链状结构。在以MEA作为还原剂的实验中,将鱼精DNA与硝酸锌溶液混合后进行凝胶电泳实验,结果出现了迁移速度比原料DNA慢的新电泳带,说明DNA吸附了锌离子,负电荷减少。随后在水浴加热条件下加入MEA水溶液,在高倍透射电子显微镜下观察产物形貌,发现纳米颗粒在DNA模板上形成链状结构,说明纳米颗粒在生长过程中DNA起到了模板的作用;X射线粉末衍射分析证明了产物为氧化锌纳米晶;紫外-可见吸收光谱分析证明了锌离子与DNA上碱基氮原子的结合。研究中还做了不添加DNA的对比试验,得到了分散的氧化锌纳米颗粒,说明没有DNA的模板作用,氧化锌颗粒不会形成链状结构。采用相似的实验方法,以HMT作为还原剂制备纳米链状结构,透射电子显微镜下观察到产物为30 nm左右的球形颗粒组成的纳米链。X射线粉末衍射分析证明了产物仍是纳米氧化锌,所以推断形成的纳米颗粒为外面包覆了一层有机配合物的氧化锌纳米晶。紫外-可见吸收光谱、红外吸收光谱、X射线光电子能谱分别证明锌离子能够与DNA上的碱基氮原子及磷酸基团相结合,生成DNA模板上的纳米颗粒,从而形成纳米链状结构。通过改变反应物浓度、反应温度、保温时间、搅拌时间等反应条件可以改变纳米链状结构的长度、团聚度等。最后,在不添加DNA的对比实验中得到了分散的球状纳米颗粒,这更加证明了DNA的模板效应。更多还原

【Abstract】 With the improved requirements for the quality of the environment, it is of great significance to develop highly sensitive and specific detection technology for environment pollutants. The introduction of nano-materials into chemical sensors is a research hot spot in analytical chemistry. Among these nano-materials zinc oxide have been paid extensive attention because of their unique mechanical, electronic properties and chemical stability. There are a variety of means to prepare nano-structured, and bio-template has been given a great deal of concern for its high-performance and low-cost.DNA is one of the most commonly used bio-template because it can absorb ions or nano-particles and its shape can be designed according to the needs. In this paper, zinc oxide nano-chains were prepared by the use of DNA template under the conditions of heating in water bath, in which zinc nitrate was acted as the reaction raw materials, while one-ethanolamine and hexamethylenetetramine acted as reducing agents.In the experiment of one-ethanolamine as reducing agent, fish sperm DNA and zinc nitrate aqueous solution were mixed for gel electrophoresis experiments. The result confirmed that zinc ions bound to DNA and decreased the negative charge of DNA because of the appearance of new DNA bands slower than raw materials DNA. Then the mixture was heated in a water-bath, and one-ethanolamine solution was added to react with zinc nitrate. High resolution transmission electron microscope (HRTEM) images showed that nanoparticles had formed along DNA template as a chain. It proved that DNA played a role of template in the growth of nanoparticles. X-ray powder diffraction analysis proved that the product was nanocrystalline zinc oxide. UV-Vis absorption spectra proved that zinc ions bound to DNA in the position of nitrogen atoms of base pairs. In control experiment with absence of DNA, dispersed zinc oxide nanoparticles were observed. This confirmed the template effect of DNA.Nano-chain structure were prepared using methods similar to the above, with hexamethylenetetramine as reducing agent. Transmission electron microscopy images showed nano-chains composed of spherical particles with the size of about 30 nm. X-ray powder diffraction analysis proved that the product was nanocrystalline zinc oxide, which inferred that the formed particles were zinc oxide nanocrystals coated with a layer of organic complexes outside. UV-Vis absorption spectrum, infrared absorption spectroscopy and X-ray photoelectron spectroscopy proved zinc ions bound to DNA in the positions of nitrogen atoms of base pairs and phosphate, then nanoparticles formed along DNA template as a chain. The length and reunion degrees of nano-chain could be controled by changing reaction conditions, such as reactant concentration, reaction temperature, holding time, stirring time,and so on. Finally, the comparison experiment without DNA as template got dispersed spherical nanoparticles, which proved the template effect of DNA in further.更多还原