硼掺杂石墨烯量子点的制备、荧光特性及分析应用

发布时间：2018-06-01 19:45

本文选题：荧光检测 + 铁离子　；参考：《南京师范大学》2017年硕士论文

【摘要】：石墨烯量子点作为一种新兴的荧光碳纳米材料,不仅具有类似传统半导体量子点的小尺寸和荧光性能,还具有低细胞毒性、化学惰性、稳定的荧光特性等优点而备受人们关注,极有希望成为在小分子检测和生物成像等荧光分析应用中传统半导体量子点的替代物。杂原子掺杂能有效调控石墨烯量子点的表面化学状态,提高荧光性能而被广泛应用于石墨烯量子点的制备过程中。本论文旨在基于硼掺杂石墨烯量子点的荧光特性,实现对水样中的铁离子及肿瘤标志物碱性磷酸酶的特异性荧光分析,为环境的保护和肿瘤的早期诊断提供快速、精准、灵敏及高效的方法。主要内容如下:(1)采用了一种简单的电化学方法合成了硼掺杂石墨烯量子点。通过施加恒电位于浸入硼砂溶液中的石墨电极,电解石墨电极获得含有硼掺杂石墨烯量子点的溶液,将所得溶液过滤,透析所得滤液并真空干燥后得到硼掺杂石墨烯量子点固体,所得硼掺杂石墨烯量子点粒径均一,发蓝色荧光,室温下可稳定存在数月。通过改变硼砂溶液的浓度,得到了不同硼掺杂量的硼掺杂石墨烯量子点,进而研究了硼掺杂石墨烯量子点的激发波长依赖和硼掺杂量依赖的荧光特性。(2)设计了一种硼掺杂石墨烯量子点荧光探针分析水样中铁离子含量。实验结果显示硼掺杂石墨烯量子点荧光信号的淬灭程度与水样中铁离子的浓度相关,但不受其他水样中可能存在的其它金属离子影响,故能实现对铁离子的特异性检测。利用光谱分析和密度泛函理论计算进一步研究了硼掺杂石墨烯量子点与铁离子之间的淬灭机理。分析结果显示水样中铁离子的浓度在0.01-100μmol/L范围内时,铁离子的浓度与所设计的荧光探针的荧光信号呈线性关系,最低检出限为0.005 ± 0.001 μmol/L,远低于WHO和EPA制定的饮用水标准中铁离子的含量(0.3ppm,5.36μmol/L),说明此方法在实际水样的检测中有巨大潜能。在三种实际水样(自来水、地表水和湖水)的检测中,检测结果与EPA推荐的原子吸收光谱法所测结果基本一致。(3)设计一种能够检测肿瘤细胞中碱性磷酸酶的表达水平的硼掺杂石墨烯量子点荧光探针。主要原理是铈离子与硼掺杂石墨烯量子点表面的羧基存在强相互作用导致硼掺杂石墨烯量子点的荧光被淬灭,当体系中存在腺苷三磷酸,细胞(如碱性磷酸酶正表达细胞:MCF-7细胞)表达的碱性磷酸酶将催化水解腺苷三磷酸产生磷酸根,水解产生的磷酸根与铈离子的强结合作用使得铈离子离开硼掺杂石墨烯量子点表面,硼掺杂石墨烯量子点的荧光得到恢复,且荧光信号的恢复程度与细胞表达的碱性磷酸酶水平相关,故基于此原理建立了分析细胞中碱性磷酸酶的方法。此法能有效避免非靶细胞的非特异性吸收的杂信号,也可用于碱性磷酸酶相关的酶的检测领域。
[Abstract]:As a new kind of fluorescent carbon nanomaterials, graphene quantum dots not only have small size and fluorescence properties similar to traditional semiconductor quantum dots, but also have the advantages of low cytotoxicity, chemical inertia, stable fluorescence properties and so on. It is very promising to be a substitute for traditional semiconductor quantum dots in fluorescent analysis applications such as small molecule detection and biological imaging. Hetero-atom doping can effectively regulate the surface chemical state of graphene quantum dots and improve their fluorescence properties, so they are widely used in the preparation of graphene quantum dots. Based on the fluorescence characteristics of boron doped graphene quantum dots, the specific fluorescence analysis of iron ions and alkaline phosphatase (ALP) in water samples was carried out in order to provide a rapid and accurate method for the protection of the environment and the early diagnosis of tumors. A sensitive and efficient method. The main contents are as follows: 1) the boron doped graphene quantum dots were synthesized by a simple electrochemical method. The solution containing boron doped graphene quantum dots is obtained by electrolysis of graphite electrode by applying a constant electric graphite electrode immersed in borax solution, and the resulting solution is filtered. The boron doped graphene quantum dots were prepared by dialyzing filtrate and vacuum drying. The boron doped graphene quantum dots were homogeneous in size and blue fluorescence. The QDs were stable for several months at room temperature. By changing the concentration of borax solution, boron doped graphene quantum dots with different boron doping amounts were obtained. The excitation wavelength dependence and the fluorescence characteristics of boron doped graphene quantum dots were studied. A boron doped graphene quantum dot fluorescence probe was designed for the determination of iron ion content in water samples. The experimental results show that the quenching degree of fluorescence signal of boron doped graphene quantum dots is related to the concentration of iron ions in water samples, but it is not affected by other metal ions in other water samples, so the specific detection of iron ions can be realized. The quenching mechanism between boron doped graphene quantum dots and iron ions was further studied by means of spectral analysis and density functional theory. The results show that when the concentration of iron ion in water is in the range of 0.01-100 渭 mol/L, there is a linear relationship between the concentration of iron ion and the fluorescence signal of the designed fluorescent probe. The lowest detection limit is 0.005 卤0.001 渭 mol 路L ~ (-1), which is much lower than that of Fe ~ (2 +) in drinking water standards set by WHO and EPA (0.3ppmN ~ 5.36 渭 mol 路L ~ (-1), indicating that this method has great potential in the detection of real water samples. In the detection of three actual water samples (tap water, surface water and lake water), The results were in good agreement with the AAS recommended by EPA.) A boron-doped graphene quantum dot fluorescence probe was designed to detect the expression of alkaline phosphatase in tumor cells. The main principle is that the existence of strong interaction between cerium ion and carboxyl groups on the surface of boron doped graphene quantum dots results in fluorescence quenching of boron doped graphene quantum dots, when adenosine triphosphate exists in the system. Alkaline phosphatase, expressed in cells such as the positive expression of alkaline phosphatase (ALP) cells, will catalyze the hydrolysis of adenosine triphosphate to produce phosphate radical. The strong binding of phosphates produced by hydrolysis to cerium ions makes the cerium ions leave the surface of boron doped graphene quantum dots and restore the fluorescence of boron doped graphene quantum dots. The recovery degree of fluorescence signal was related to the level of alkaline phosphatase expressed in cells, so a method for analyzing alkaline phosphatase in cells was established based on this principle. This method can effectively avoid the non-specific absorption of non-target cells and can also be used for the detection of alkaline phosphatase related enzymes.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O657.3

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