【作者】 国大旺；

【导师】 周伟红；

【作者基本信息】 吉林大学 ， 分析化学， 2011， 博士

【摘要】 重金属在现代工业、农业、医药等领域有着广泛的应用,但是随着现代工业和运输业的发展,重金属污染的环境问题日益突出。重金属难以降解,会在生物体内长期积累,即便极其微量也可能产生严重后果。重金属通过食物链沉积到人体后,可引起各种疾病,对人类健康造成严重损害。因此重金属检测在环境、农产品中残留监测中非常重要。本文主要针对当前常见的几种重金属离子,设计了几种具有不同灵敏度的检测方法,以满足对不同环境中重金属离子检测的需要。在开发针对重金属检测方法的同时也对碲化镉量子点对常青藤光合作用的影响进行了初步研究。工作重点主要涉及以下几个方面:1、基于寡核苷酸的Hg（Ⅱ）的传感器的制备及Hg（Ⅱ）的检测包含G碱基重复序列的DNA链,能够在K⁺和血红素的作用下,形成类似过氧化物氧化酶的DNAzyme,而T碱基与Hg²⁺之间能特异性结合,形成T-Hg²⁺-T的结构。利用DNA的这两个特性,本工作中设计了两种具有特殊构成的寡核苷酸链,分别用于Hg²⁺目视比色传感器和化学发光传感器的制备,并通过目视比色法和化学发光法对水溶液中的Hg²⁺进行了检测,检测限分别为1×10^-10 mol L^–1和2.5×10^-9 mol L^–1。2、Nafion稳定的纳米银汞齐修饰电极的制备及其对Pb²⁺、Cd²⁺、Cu²⁺的检测不同于以前固体汞齐电极的制备,本实验中利用nafion为软模板,通过电化学方法使Ag⁺和Hg²⁺在线还原,并在玻碳电极表面形成稳定的纳米级的银汞齐,通过扫描电子显微镜照片证明生成的纳米银汞齐的直径约为50 nm。实验过程中避免了与液态Hg的接触,减少了Hg的用量,并且通过生成银汞齐及nafion对Hg的稳定作用实现了Hg的固定,减少了电极的毒性。利用该方法制得的修饰电极在重金属离子的检测中具有稳定、灵敏、线性范围宽、重现性好的特点。通过对自来水中Cd²⁺、Pb²⁺、Cu²⁺三种金属离子的同时检测,进一步验证了该电极用于实际样品检测的可行性。同时该方法也可推广到其它基底修饰的电极中,应用前景非常广阔。3、以硫代苹果酸为显色剂可视化检测Fe³⁺铁不仅在地壳中分布广,而且是动植物中最重要的元素之一,它在许多化学和生理过程中扮有重要的角色。人体血液中的铁必须保持在一定的浓度,过多或过少都会对人体健康造成极大的危害,因此发展方便、快速、廉价的检测方法具有重要意义。通过实验证明,硫代苹果酸能够高选择性地与溶液中的三价铁离子络合并形成紫色络合物,该紫色络合物在体系pH为8.0时能够稳定存在,而且颜色随三价铁离子浓度的改变变化明显,能够用于三价铁离子的快速、灵敏检测。同时还证明本方法适用于人血中铁元素检测,在铁元素检测的常规化方面具有很好的应用前景。4、杯[4]芳烃羧酸填充的微萃取柱通过流动注射和火焰原子吸收光谱联用对水样中的微量重金属进行在线富集和检测本工作中利用杯[4]芳烃羧酸填充的微柱将流动注射在线预富集和火焰原子吸收光谱仪联用,对水样中的Cu²⁺、Pb²⁺、Co²⁺、Ni²⁺、Cd²⁺进行了检测。该方法可以将流动注射在线预富集快速稳定的优势与火焰原子吸收光谱法灵敏、选择性好的优势较好的结合起来。通过对实验条件如:样品的pH值、装载时间、流速以及洗脱液的浓度、体积、流速等的优化,在对Cu²⁺、Pb²⁺、Co²⁺、Ni²⁺、Cd²⁺进行检测时,显示出了低检出限,高富集倍数和高样品通量的特点;在对标准品中目标金属的检验中,检验结果与参考值相符合。此外,通过回收实验证明:该方法能够用于实际水样中Cu²⁺、Pb²⁺、Co²⁺、Ni²⁺、Cd²⁺的检测,具有很好的实用性。5、碲化镉量子点在紫外光下对常青藤光合作用影响的研究通过对所合成的量子点的荧光波长进行选择以及常青藤叶片光合作用的最终产物—淀粉的检测,发现所选CdTe能够有效的吸收紫外线的能量并将能量转移给植物的光合反应中心,从而使得光合作用能够在紫外线下进行。CdTe的引入扩大了植物可利用的光谱范围,使原来对植物光合系统造成损害的紫外光能为其所用。另外通过对单位质量叶片叶绿素含量的检测以及显微镜下对叶绿体形貌观察及数量的统计发现,CdTe量子点并不仅仅是充当接收紫外线的角色,它还通过和叶绿体之间的能量交换,有效地保护植物的光合系统不受紫外线的伤害。虽然所用量子点中含有重金属镉,但是其独特的光学特性,使其在光合作用的研究中占有得天独厚的优势,是研究光合作用机理、紫外线伤害防止、光合作用效率提高的强有力工具。更多还原

【Abstract】 Heavy metals have been used widely in manufacture, agriculture and pharmaceuticals industry, however, as the rapid development of modern industrial and transport, the environmental heavy metals pollution become more and more serious. Heavy metals cannot be rendered harmless by chemical or biological remediation processes and can persist in body of human and animals for long periods. Through the food chain heavy metals may deposit into human and animals body and even a little quantity can cause serious health problems which could transfer to the next generation on the genetic level. So in environmental and agricultural food monitoring it is very important to quantitatively analyze heavy metals. In this study several different methods with different sensitivities were developed to the determination some of the most common heavy metals. Besides researches of heavy metals determination, the effect of CdTe quantum dot on the photosynthetic systems of plant under ultraviolet-B radiation was also studied.1. The preparation of oligonucleotide based Hg²⁺ sensor and the application in Hg²⁺ determination.In this study a highly sensitive chemiluminescence sensor and a highly sensitive colorimetric sensor for the detection of Hg²⁺ in aqueous solution were developed by using two kind of thymine （T）-rich, mercury-specific oligonucleotide （MSO） probe. The MSO probes can form G-quadruplex DNAzyme on the effect of k+ and hemin. Mismatched thymine-thymine （T-T） base-pairs can take up the mercury ion and form inter-strand T-Hg²⁺-T complexes, which can affect the formation of DNAzymes. Through investigating the signal changes of luminol-H2O2 system （chemiluminescence） and TMB-H2O2 system （colorimetric） Hg²⁺ could be quantitative detected. The detection limit were 1×10^-10 mol L-1and 2.5×10^-9 mol L^-1respectively.2. Nafion film immobilized nano Ag-Hg amalgam glassy carbon electrode used for simultaneous determination of lead, cadmium and copperIn this work, a new route to reduce the toxicity of the mercury electrode was presented. Nafion was used as soft template to generate nanosized Ag-Hg amalgams on the surface of a glassy carbon electrode other than the traditional preparation of solid amalgam electrodes. As less mercury was used and it was immobilized by Ag and nafion film, the toxicity of mercury was reduced. Scanning electron microscope （SEM） showed that the size of the formed nano Ag-Hg amalgams was about 50 nm. Finally, the prepared electrode was used to the determination of heavy metals. Good reproducibility, linearity and sensitivity were obtained when it was utilized for the determination of Cd²⁺, Pb²⁺ and Cu²⁺ in deionized water and in tap water （without any further treatment）. Different from the general methods of preparing amalgam electrodes, the method used in this work is more simple and possible to be used on different substrate materials.3. Visual determination of iron （Ⅲ） with mercaptosuccinic acid as color developing reagentIn this work, a simple, economical and sensitive method for Fe³⁺ determination with naked eye was presented inμg mL^-1 level. For the first time, mercaptosuccinic acid （MSA） was used to form a stable purple complex with Fe³⁺ at pH 8.0. When different quantities of Fe³⁺ were added, the color of the complex changed, which was sensitive enough to be observed with naked eye. Effects of pH and MSA concentrations were discussed to optimize the experimental conditions. Under the optimum conditions, the corresponding relationship between Fe³⁺ concentration and the color of the complex system was studied in the concentration range of 0.5-100μg mL-1. In addition, the method showed good selectivity for Fe³⁺ over Ni²⁺, Pb²⁺, Mn²⁺, Cr³⁺, Cu²⁺ and Co²⁺ when 1, 2-ethylenediamine was used as the masking agent. The feasibility of the method in the visible determination of the content of full iron (both Fe³⁺ and Fe²⁺) in human whole blood samples was approved.4. On-line preconcentration and determination of trace metals in water samples by flow injection combined with flame atomic absorption spectrometry using calix[4]arene carboxylic acid packed micro-columnThe results obtained in this work indicate that the combination of FI on-line preconcentration with FAAS is an efficient and simple method when using a micro-colum packed with calix[4]arene carboxylic acid. The developed method exhibits an excellent configuration, joining the advantages of flow injection preconcentration in terms of speediness and robustness to those of FAAS in terms of sensitivity and selectivity. When used for the determination of heavy metal ions, Cu²⁺, Pb²⁺, Co²⁺, Ni²⁺, and Cd²⁺, the present strategy provides low limits of detection, high enrichment factors and throughput after the experimental parameters have been optimized, i.e., sample pH, loading time, flow rate, and eluent concentration, volume, and flow rate. The analytical results of the target metals in certified reference materials with the present method are in good accordance with the certified values. In addition, the method has been assessed through recovery experiments when employed for the determination of trace Cu²⁺, Pb²⁺, Co²⁺, Ni²⁺, and Cd²⁺ in water samples.5. Study on the effect of CdTe quantum dots on the photosynthetic systems of Ivy under ultraviolet-B radiationWater soluble CdTe quantum dots （QDs） were synthesized and the photoluminescence wavelengths of these QDs were optimized to get the best energy transfer between CdTe QDs and the photosynthetic systems of Ivy leaves. It was well known that amylum can be produced through photosynthesis of plants and the quantum of amylum can reflect the effection of photosynthesis. Through detection of amylum it was found that the introduction of CdTe QDs can enhance the light-harvesting process and enable Ivy to absorb sunlight in a much broader spectral range. Further more, through investigation of the shape of chloroplast and counting of the number of chloroplast by cell counting chamber, it was found that CdTe QDs can reduce the harm brought by ultraviolet-B radiation.更多还原