碳点荧光性能的调控及其荧光猝灭的研究

发布时间：2018-06-26 04:25

本文选题：碳点 + 调控　；参考：《西南大学》2015年硕士论文

【摘要】：自2004年,Xu等首次发现了荧光碳点后,它成为了继富勒烯、碳纳米管及石墨烯之后最热门的碳纳米材料之一,引起了人们的广泛关注。碳点具有荧光强度高、耐光漂白、无光闪烁现象、发射波长可调控等优良荧光性能,同时又有生物相容性好、毒性低、原料易得、制备方法简便等优点。基于这些优点,碳点有望取代量子点进行生物成像,可作为一种可观察性和可追踪性的新型的药物载体,也可设计探针检测金属离子、阴离子、有机小分子及生物分子。此外,碳点因为优异的物理化学性能(如光诱导电子转移、氧化还原性),在光催化剂这一领域有很好的应用前景以及应用于发光材料,如激光、LED、荧光油墨等。尽管碳点有很多的优点和研究应用,但是碳点的单颗粒荧光比量子点的弱；碳点的发射波长主要集中在蓝光和绿光区域。尽管有文献报道,大多数碳点的发射随激发的变化而变化,即激发依赖型。但是当激发波长偏离最佳激发态较多时荧光强度很弱。总之,碳点的荧光性能还不能和量子点相比,这成了限制碳点应用的瓶颈。因此,调控碳点的荧光性能是非常必要且迫切的。本文就主要对调控和研究碳点的荧光性能做了以下研究：(1)分别以NaBH4和LiAlH4作为还原剂还原油烟碳点,得到还原程度不同的两种碳点,分别记为r-CDs1和r-CDs2,成功的调控了碳点的激发、发射和荧光量子产率。而且经过还原处理后,原先某些性能差的碳点可进一步生长为性能较好的碳点。并经实验证实,碳点荧光性能的改变与粒径无关,而与表面基团的改变有关。同时,我们还通过计算能隙和第一激发能解释了还原反应调控发射波长的机制。本工作为调控碳点的荧光性能、设计纳米荧光探针提供了新思路。(2)纳米金由于在紫外-可见光区域内具有较宽的吸收范围和较大的吸收系数,这使得它有显著的猝灭效果,是一种很好的荧光猝灭剂。而碳点的荧光能被多种荧光猝灭剂所猝灭,基于此,我们首次研究了纳米金作为一种荧光猝灭剂对碳点荧光的猝灭行为。考察了碳点浓度、pH值、反应温度和时间等多种因素对荧光猝灭的影响,在最佳实验条件下猝灭常数为9.1×108 L mol-1。此外,因为加入猝灭剂纳米金前后碳点的荧光寿命基本不变；且随温度升高,猝灭常数减小。因此,推测纳米金对碳点的荧光猝灭为静态猝灭。
[Abstract]:Since Xu et al discovered the fluorescent carbon point for the first time in 2004, it has become one of the most popular carbon nanomaterials after fullerene, carbon nanotubes and graphene. Carbon spots have the advantages of high fluorescence intensity, high photobleaching resistance, no light scintillation, adjustable emission wavelength, good biocompatibility, low toxicity, easy to obtain raw materials and simple preparation methods. Based on these advantages, carbon dots are expected to replace quantum dots for biological imaging, which can be used as a new drug carrier with observability and traceability, and can also be designed to detect metal ions, anions, organic small molecules and biomolecules. In addition, because of its excellent physical and chemical properties (such as photoinduced electron transfer, redox), carbon has a good application prospect in the field of photocatalyst, and can be used in luminescent materials such as laser photoresist, fluorescent ink and so on. Although carbon dots have many advantages and applications, the single particle fluorescence of carbon dots is weaker than that of quantum dots, and the emission wavelengths of carbon dots are mainly concentrated in the region of blue and green light. Although it has been reported that the emission of most carbon points varies with the excitation, that is, the excitation dependent type. However, the fluorescence intensity is very weak when the excitation wavelength deviates from the optimal excited state. In a word, the fluorescence properties of carbon dots can not be compared with those of quantum dots, which has become the bottleneck limiting the application of carbon dots. Therefore, it is very necessary and urgent to regulate the fluorescence properties of carbon points. In this paper, the fluorescence properties of carbon points were studied as follows: (1) reducing oil fume carbon points with NaBH4 and LiAlH4 as reductants, two carbon spots with different reduction degree were obtained, which were recorded as r-CDS1 and r-CDs2 respectively, which successfully regulated the excitation of carbon points. Emission and fluorescence quantum yields. After reduction, some poor carbon points can be further grown into better carbon points. The experimental results show that the change of the fluorescence properties of carbon points is independent of the particle size, but related to the change of the surface groups. At the same time, we calculate the energy gap and the first excitation energy to explain the mechanism of controlling the emission wavelength of the reduction reaction. This work provides a new idea for controlling the fluorescence properties of carbon spots and designing nanoscale fluorescence probes. (2) because of its wide absorption range and large absorption coefficient in the UV-visible region, the nano-gold has a remarkable quenching effect. It is a good fluorescence quenching agent. The fluorescence of carbon point can be quenched by a variety of fluorescence quenching agents. Based on this, we have studied the quenching of carbon point fluorescence by nano-gold as a fluorescence quenching agent for the first time. The effects of pH, reaction temperature and time on fluorescence quenching were investigated. The quenching constant was 9.1 脳 10 ~ 8 L mol ~ (-1) under the optimum experimental conditions. In addition, the fluorescence lifetime of carbon point is almost unchanged before and after the addition of the quencher, and the quenching constant decreases with the increase of temperature. Therefore, it is inferred that the fluorescence quenching of carbon point by gold nanoparticles is static quenching.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TB383.1

【参考文献】