碳点的合成、性能及其生物传感应用研究

发布时间：2018-04-20 19:46

本文选题：聚乙烯亚胺 + pH敏感型碳点　；参考：《东北大学》2015年博士论文

【摘要】：碳点(CDs)不仅具备碳纳米材料的共同特性,如对环境和生物体无毒,合成方法多种多样,表面官能团丰富等,而且作为新型的发光碳纳米材料,其量子产率最高可达80%,与半导体量子点(QDs)相当。因而,碳点成为近年来碳纳米材料的研究热点。用不同方法和原料制备的CDs可在多个领域获得广泛应用,因此,合成碳点的新方法仍是目前亟待探索的领域。碳点的量子产率高,发射光谱可调,然而,迄今为止,其发光机理尚无定论。CDs表面官能团丰富,多被用于表面改性和偶联生物分子,实现特异性传感和靶向成像、治疗等目标。另一方面,表面官能团的氧化还原性质尚未得到深入研究。在传感应用领域,以CDs荧光信号的猝灭或增强构建的传感器是目前的研究热点,而基于CDs其他物理化学性质,如氧化还原性的探针的研究还未见报道。本文旨在拓展CDs合成方法和原料,研究表面官能团对其发光性能的影响,探讨表面官能团的还原性,并利用CDs的还原性构建新型传感器。论文的第一章详细介绍了CDs的合成方法,物理化学性质及其在光学成像、载药治疗、光学传感和光催化等领域的应用。论文的第二章以阳离子型聚电解质聚乙烯亚胺(PEI)同时作为碳源和表面钝化剂,化学氧化法一步制备PEI-CDs。PEI被HNO3分解,部分PEI片段被碳化并氧化,得含氧碳核；未反应的PEI片段通过酰胺化与碳核表面的羧基反应,得到表面同时富含氨基和羧基的PEI-CDs。该碳点在酸性条件下带正电,碱性条件下带负电。表面氨基和羧基在酸性和碱性介质中质子化和去质子化,使得PEI-CDs的荧光对溶液pH变化表现灵敏响应,即随着pH的升高,荧光强度显著下降。PEI-CDs的荧光对pH变化的响应可逆：将pH从2增加到12,再从12降低到2,10次循环变化后,碳点荧光依然恢复初始值。PEI-CDs的荧光不受盐浓度和光辐照的影响,盐浓度高达1 mol L-1,或150 W氙灯连续激发3h,其发光强度无改变。HeLa细胞同PEI-CDs孵育24 h,未见明显细胞毒性。PEI-CDs穿透细胞膜,进入到细胞质。进入细胞的PEI-CDs在340 nm和495 nm光源激发下,分别发射蓝色和绿色荧光。在合成CDs的研究中,其表面丰富的官能团吸引了我们的注意,因此第三章主要研究表面官能团的氧化还原性。无须光辐照和外加还原剂,Ag+同CDs的水溶液在50℃下水浴5 min, Ag+被还原为Ago,随后Ago自发团聚成核,生成平均粒径为3.1±1.5nm的Ag-NPs。CDs表面的酚羟基和氨基还原Ag+后分别转换成苯醌和偶氮。生成的Ag-NPs吸附在CDs表面,形成Ag-NPs/CDs复合物。其中CDs充当保护剂,使Ag-NPs在水溶液中稳定分散至少45天,而未见团聚。CDs催化还原生成的Ag-NPs有强共振光散射(RLS),而且RLS的信号强度与Ag+的浓度线性相关,基于此,我们建立了环境水样中Ag+含量的分析方法。对两种河水样的加标回收率分别为103%和106%,测定结果满意。CDs还可还原HAuCl4并生成粒径为3.0±0.7m的Au-NPs。制备Ag-NPs和Au-NPs的最优条件分别是弱碱性和弱酸性介质,这是因为CDs在碱性条件下带负电,而在酸性条件下带正电,分别适宜结合Ag+和AuCl4-。在研究Ag-NPs生成的最优条件时,发现过量的CDs显著抑制Ag-NPs的生长,我们在第四章中对这一有趣的实验现象进行了深入探索。研究发现,体系中CDs过量,Ag+迅速吸附到CDs表面,溶液中自由的Ag+数量少,不能源源不断地供应Ag+到CDs表面,Ag-NPs的生长被阻断,因而生成量减少。加入生物硫醇后,巯基同Ag++结合,二者迅速形成络合物。由于生物硫醇的还原能力比CDs弱,络合物逐步释放Ag+,供应Ag+给CDs表面官能团还原,因而体系中Ag-NPs生成量增多。以增强的Ag-NPs表面等离子体共振吸收峰强度为信号,定量检测生物硫醇。当Ag+加入量为0.2 mM时,半胱氨酸(cys)的检测范围是20-400 nM。减少体系中的Ag+,可以进一步增强生物硫醇传感的灵敏度。即当Ag+加入量为0.1 mM时,体系对Cys,高半胱氨酸(Hcy)和谷胱甘肽(GSH)三种生物硫醇的传感范围分别是2.5-30 nM、5-40 nM和2.5-30 nM。实际样品中常见的共存组分,如19种氨基酸,Ca2+, Mg2+,葡萄糖,抗坏血酸和人血清白蛋白对生物硫醇的检测无干扰。将该体系用于人血样中生物硫醇的定量检测,加标回收率为94-108%。
[Abstract]:Carbon point (CDs) not only has the common characteristics of carbon nanomaterials, such as non-toxic to the environment and organism, many kinds of synthetic methods and rich surface functional groups. Moreover, as a new kind of luminescent carbon nanomaterials, the quantum yield is up to 80%, which is equivalent to the semiconductor quantum dots (QDs). Therefore, the carbon point has become the research heat of carbon nanomaterials in recent years. CDs, prepared with different methods and raw materials, can be widely used in many fields. Therefore, the new method of carbon point synthesis is still an urgent field. The quantum yield of carbon point is high and the emission spectrum is adjustable. However, so far, its luminescence mechanism is not conclusive on the rich.CDs surface functional groups, and is used for surface modification and coupling organisms. Molecules, the realization of specific sensing and target imaging, treatment and other targets. On the other hand, the redox properties of surface functional groups have not been deeply studied. In the field of sensing applications, the quenching or strengthening of CDs fluorescence signals is a hot spot of research, based on other physical and chemical properties of CDs, such as redox probes. The purpose of this study is to expand CDs synthesis methods and materials, to study the effect of surface functional groups on their luminescence properties, to explore the reducibility of surface functional groups and to construct new sensors using the reducibility of CDs. The first chapter of the paper describes the synthesis method of CDs, the physical and chemical properties and the treatment of the optical imaging and drug loading. The second chapter of the paper uses cationic polyelectrolyte polyethyleneimine (PEI) as a carbon source and a surface passivating agent. PEI-CDs.PEI is decomposed by HNO3 in one step by chemical oxidation. Some PEI fragments are carbonized and oxidized to obtain oxygen containing carbon nuclei; the unreacted PEI fragments pass amidation and carbon nuclei. The surface of the carboxyl group reacts with the PEI-CDs., which is rich in the amino and carboxyl groups at the same surface. The carbon point is positive under the acidic condition and is negative under the alkaline condition. The surface amino and carboxyl groups are protonated and deprotoned in the acidic and alkaline medium, making the fluorescence of PEI-CDs responsive to the pH change of the solution, that is, with the increase of pH, the fluorescence intensity is increased. The response of the fluorescence of.PEI-CDs to the change of pH is reversible: the increase of pH from 2 to 12, and then from 12 to the 2,10 secondary cycle, the fluorescence of the carbon point is still restored to the initial value.PEI-CDs, without the effect of salt concentration and light irradiation, the concentration of the salt is up to 1 mol L-1, or the 150 W xenon lamp is continuously excited 3h, and the luminescence intensity does not change.HeLa cells and P. EI-CDs incubated 24 h, no obvious cytotoxic.PEI-CDs penetrated the cell membrane and entered the cytoplasm. The PEI-CDs of entering cells fired blue and green fluorescence respectively under the excitation of 340 nm and 495 nm light sources. In the study of the synthesis of CDs, the rich surface of the functional groups attracted our attention, so the third chapter mainly studied the oxygen of surface functional groups. Without light irradiation and external reductant, the water solution of Ag+ and CDs is bathing at 50 C for 5 min, Ag+ is reduced to Ago, then Ago spontaneously agglomerated into nucleation, and the phenolic hydroxyl and amino group of Ag-NPs.CDs surface with an average diameter of 3.1 + 1.5nm are converted into quinone and azo respectively after reducing Ag+, and Ag-NPs is adsorbed on CDs surface to form Ag-NPs. The /CDs complex, in which CDs acts as a protector, makes Ag-NPs stable and dispersed in aqueous solution for at least 45 days, and there is no strong resonance light scattering (RLS) of Ag-NPs generated by the reunion.CDs catalytic reduction, and the signal intensity of RLS is linearly related to the concentration of Ag+. Based on this, we have established an analytical method of Ag+ content in the water samples in the environment. For the two kinds of water samples. The recovery rate of the addition standard is 103% and 106% respectively. The results are satisfied that.CDs can also reduce HAuCl4 and produce Ag-NPs and Au-NPs with a diameter of 3 + 0.7m. The optimum conditions for preparing Ag-NPs and Au-NPs are weakly alkaline and weak acidic medium respectively. This is because CDs is negatively charged under alkaline conditions and is positively charged under acidic conditions, suitable for combining Ag+ and AuCl4-. to study respectively. When investigating the optimal conditions for Ag-NPs generation, we found that excessive CDs significantly inhibited the growth of Ag-NPs. In the fourth chapter, we explored this interesting experimental phenomenon. It was found that CDs overdose, Ag+ quickly adsorbed to the surface of CDs, and the free Ag+ quantity in the solution was less, and could not supply Ag+ to CDs surface, Ag-NPs. After the length was blocked, the amount of raw material decreased. After the addition of bio mercaptan, the sulfhydryl group combined with Ag++, the two quickly formed the complex. Because the reduction ability of the bio mercaptan was weaker than that of CDs, the complex gradually released Ag+ and supplied Ag+ to the CDs surface functional group. Therefore, the formation of Ag-NPs in the system increased much. The enhanced Ag-NPs surface plasmon resonance absorption peak was increased. The intensity is a signal, quantitative detection of bio mercaptan. When Ag+ is added to 0.2 mM, the detection range of cysteine (Cys) is the Ag+ in the 20-400 nM. reduction system. It can further enhance the sensitivity of biothiol sensing. That is, when Ag+ is added to 0.1 mM, the system is sensing of Cys, high cysteinic (Hcy) and glutathione (GSH) three biogenic mercaptan. The range is the common component in the actual samples of 2.5-30 nM, 5-40 nM and 2.5-30 nM., such as 19 kinds of amino acids, Ca2+, Mg2+, glucose, ascorbic acid and human serum albumin have no interference to the detection of biogenic mercaptan. The system is used for quantitative detection of biogenic mercaptan in human blood samples, and the recovery rate is 94-108%.

【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11;TP212

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