锗、氮原子掺杂碳点的可控合成及其在生化分析中的研究

发布时间：2018-06-22 12:51

本文选题：锗掺杂的碳点 + 氮掺杂的碳点　；参考：《西南大学》2016年硕士论文

【摘要】：碳点(carbon dots)一般是指粒径小于10 nm的碳纳米材料。由于其独特的光学性质和优良的生物相容性,碳点已经成为超越荧光分子和量子点的材料,引起了无数研究者的关注,并且已被用于生物成像、分析检测、光电催化,以及能量转移等方面。然而,对于碳点的发光机理、不同光学性质碳点的合成、以及在碳点表面引入不同的功能化基团的相关报道还较少。为了更好地了解碳点并开发其实用价值,我们应该对这些方面进行更深入的研究与探讨。本文合成了一系列用柠檬酸(CA)作为碳源的碳点。在表征其发光性质、探索其发光机制的基础上,做了以下研究:(1)将锗掺杂的碳点作为一种新型荧光探针用于可视化动态监视汞离子入侵细胞。本文首次将柠檬酸与羧乙基锗倍半氧化物分别做为碳源与锗源,用一种简单快速(15 min)的碳化法合成了锗元素掺杂的碳点(GeCDs)。不同于大多数碳点的发射波长对激发波长的依赖,GeCDs的发射波长不依赖激发波长。GeCDs具有细胞毒性低、生物相溶性好、化学性质稳定的特点。更重要的是,GeCDs能够在金银花露溶液或细胞溶液等极其复杂的环境中与汞离子特异结合。此外,GeCDs还可作为一种新型探针,用于在人喉癌细胞(HEp-2)中实时监测汞离子入侵细胞的过程,以及可视化监测汞离子引起的细胞重大生理变化。(2)通过调节表面状态可控合成具有不同光学性质的氮掺杂的碳点本文以柠檬酸与盐酸胍为原料合成了一系列碳材料,其中一部分表现出发射波长依赖激发波长的性质(EDE),另一部分表现出发射波长不依赖激发波长的光学性质(EIE)。同时,这些碳材料具有化学性质稳定、对细胞的毒性低、生物相容性好的特点。通过对碳点表面状态的调节,可以改变碳点的光学性质(例如EDE,EIE,荧光量子产率等)。对实验数据的分析表明,碳点表现出不同光学性质的原因在于表面状态的差异。如果碳点表面被盐酸胍完全钝化,碳点表现为EIE特征,量子产率可以高达60.5%。如果表面钝化程度低,碳点表现为EDE特征。分析还发现,汞离子可以与这些碳点特异性地结合,致使碳点荧光猝灭。该现象可以用电子转移能级重叠解释,即碳点LUMO能级上的电子转移到汞离子上,而不是回到HOMO能级,致使碳点不能发射出荧光。由于本文合成的碳点化学性质稳定,且与汞离子有特殊作用,故可作为一种有效的荧光探针,可视化监测细胞内的汞离子浓度。
[Abstract]:Carbon point (carbon dots) usually refers to carbon nanomaterials with diameter less than 10 nm. Because of their unique optical properties and excellent biocompatibility, carbon dots have become materials beyond fluorescent molecules and quantum dots, which have attracted the attention of numerous researchers and have been used in biological imaging, analytical detection, photocatalysis, And energy transfer and so on. However, there are few reports on the luminescence mechanism of carbon points, the synthesis of carbon spots with different optical properties and the introduction of different functionalized groups on the surface of carbon spots. In order to better understand the carbon point and develop its practical value, we should study these aspects more deeply. A series of carbon spots with citric acid (CA) as carbon source have been synthesized. On the basis of characterizing its luminescence properties and exploring its luminescence mechanism, the following studies have been done: (1) the germanium doped carbon point is used as a new fluorescent probe to visualize the dynamic monitoring of mercury ion invasion cells. It is the first time that citric acid and carboxyethyl germanium semicoxide are used as carbon source and germanium source respectively. GE doped carbon spots (GeCDs) were synthesized by a simple and fast carbonization method (15 min). Different from the emission wavelengths of most carbon spots, the emission wavelengths of GeCDs do not depend on the excitation wavelengths. GeCDs have the characteristics of low cytotoxicity, good biocompatibility and stable chemical properties. More importantly, GeCDs can specifically bind to mercury ions in extremely complex environments such as honeysuckle solution or cell solution. In addition, GeCDs can be used as a new probe for real-time monitoring of mercury ion invasion in human laryngeal cancer cells (HEp-2). Visual monitoring of cellular physiological changes induced by mercury ions. (2) nitrogen doped carbon spots with different optical properties were synthesized by adjusting the surface state. A series of carbon materials were synthesized from citric acid and guanidine hydrochloride. Some of them show the properties of emission wavelength dependent on excitation wavelength (EDE) and the other part show optical property of emission wavelength independent of excitation wavelength (EIE). At the same time, these carbon materials have the characteristics of stable chemical properties, low cytotoxicity and good biocompatibility. By adjusting the surface state of the carbon point, the optical properties of the carbon point can be changed (such as EDEE, fluorescence quantum yield, etc.). The analysis of the experimental data shows that the difference of surface states is the reason for the different optical properties of carbon spots. If the surface of the carbon spot is completely passivated by guanidine hydrochloride, the carbon spot is characterized by EIE, and the quantum yield can reach 60.5%. If the surface passivation is low, the carbon point is characterized by EDE. It is also found that mercury ions can specifically bind to these carbon spots, resulting in fluorescence quenching of carbon spots. This phenomenon can be explained by the overlap of electron transfer energy levels, that is, the electrons on the LUMO level of the carbon point transfer to the mercury ion instead of returning to the Homo level, resulting in the emission of fluorescence from the carbon point. Due to the stable chemical properties of the carbon points synthesized in this paper and its special role with mercury ions, it can be used as an effective fluorescence probe to visually monitor the concentration of mercury ions in cells.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O613.71;O657.3

【相似文献】