CdS纳晶电致化学发光性能的提升与生物传感应用

发布时间：2018-01-28 10:48

本文关键词： 电致化学发光 CdS纳晶 ECL共振能量转移核酸包裹的Ag纳米簇 microRNA检测原位活化 H_2S检测　出处：《南京大学》2015年硕士论文　论文类型：学位论文

【摘要】：电致化学发光(Electrochemiluminescence,ECL)是一类由电氧化还原产生的化学发光,因此它既有电化学的优势也有化学发光的优点。并且相比于荧光、光致发光等其他光分析手段,电致化学发光不需要额外的激发光源,背景信号低。此外,ECL检测方法还具有灵敏度高、不需要昂贵的检测仪器等优势。半导体纳晶(NCs)作为新型的ECL材料,由于其具有种类多,合成简单,光电性质易于调控等优点,不仅被广泛应用在ECL生物标记和ECL生物传感器中,还催生了很多新的分析原理和方法。NCs与传统的发光试剂如Ru(bpy)32+相比,其ECL的强度通常较弱。我们课题组在前期的研究中发展了多种提升ECL性能的方法,并建立了多种基于共振能量转移(RET)的ECL生物分析方法。本论文发现了新型的ECL供受体对,用于microRNA生物小分子的检测中。另外我们发展了一种简单的表面化学处理的方法用于提升CdS NCs的ECL性能,并将其用于生物体系中H2S浓度的检测。具体开展了以下两方面的工作：1.以核酸包裹的银纳米簇为标记对microRNA进行电致化学发光与电化学双信号检测本工作中我们使用核酸包裹的银纳米簇提出了一种新型、灵敏、特异性地检测microRNA浓度的分析方法。当目标microRNA存在时,由于核酸包裹的Ag纳米簇的紫外-可见吸收光谱与CdS NCs的ECL发射光谱重叠良好,因此来自滴涂在玻碳电极表面CdS NCs的ECL可被近距离接触的Ag纳米簇猝灭。同时,由于导电性的Ag纳米簇可加速电子传递,因此共反应剂K2S208的还原峰电流可以被增强。这样,CdS NCs的ECL强度的猝灭现象与K2S208还原峰电流的增强现象可以共同表明同一种生物结合事件。这种检测方法可以灵敏地检测microRNA的浓度,检测范围为10 fM至1 nM。因此,我们相信这项研究工作可以用于发展其他多种生物传感器。2. CdS NCs电致化学发光膜的原位活化及其在H2S检测中的应用我们提出了一种简单的原位活化方法,将滴涂在玻碳电极(GCE)上的CdSNCs膜(CdS NCs/GCE)浸泡在含有H2O2和柠檬酸的活化液中,使得在有H2O2作为共反应剂时其ECL光强提升了约58倍。在活化过程中,CdS NCs被H2O2氧化,粒径减小并有更多的表面S缺陷生成；同时,柠檬酸在稳定NCs方面起重要作用。此外我们对ECL增强机理进行了详细探讨,活化中H2O2与CdS NCs表面过量的Cd2+离子(S缺陷)的吸附作用是主要因素,这种吸附作用能稳定H2O2在电化学过程中产生的OH·自由基,使得更多的(CdS)·-被其氧化生成激发态,导致ECL信号的增强。另外,活化后纳米晶膜变得更薄,且致密度下降,这不仅使表面积增大,暴露更多的表面S缺陷,而且促进了ECL检测液中的小分子如共反应剂H2O2等向膜内的扩散。由于S(Ⅱ)与CdS NCs表面过量Cd2+离子的结合作用,活化后的CdSNCs/GCE在Na2S溶液中浸泡后,其ECL信号被猝灭,据此,我们以活化后的CdS NCs/GCE作为ECL探针用于检测Na2S浓度,结果表明其ECL信号的猝灭程度与Na2S浓度的对数成线性相关,线性范围较宽,为5nM-20μM,且选择性良好。最后,我们将这种ECL探针成功地应用于生物体系中H2S浓度的检测。
[Abstract]:Electrochemiluminescence (Electrochemiluminescence, ECL) is a kind of chemical produced by electro oxidation reduction of light, so it has the advantage of electrochemical also has advantages of chemiluminescence. And compared to other light emitting means of fluorescence analysis of light induced, electrochemiluminescence does not need additional excitation light source, low background signal. In addition, ECL detection method has high sensitivity, does not require expensive instrumentation and other advantages. The semiconductor nanocrystals (NCs) as a new type of ECL material, because of its variety, simple synthesis, optical properties and easy to control, not only is widely used in ECL biological markers and ECL biosensors, also spawned a lot of new luminescent reagents such as Ru analysis principle and method with the traditional.NCs (bpy) 32+ compared to its ECL strength are often weak. Our previous study in the development of a variety of approaches of elevating the performance of ECL, and The establishment of a variety of resonance energy transfer (RET) based on ECL analysis method. This paper found biological model for ECL receptor on, for the detection of microRNA biological small molecules. We also developed a simple method of surface chemical treatment for ECL to improve the performance of CdS NCs, which is used to detect the concentration of H2S in biological systems. To carry out specific work in the following two aspects: 1. silver nanoclusters encapsulated electrical marker nucleic acid on microRNA induced chemiluminescence and electrochemical double signal detection of silver nanoclusters in this work, we use DNA wrapped presents a novel, sensitive analysis method to detect the microRNA concentration of specific. When the target. The presence of microRNA, the UV - Ag nanoclusters DNA wrapped the visible absorption spectra of CdS NCs and ECL emission spectra overlap, so from the drop onto the surface of glassy carbon electrode CdS NCs E Ag nanoclusters quenching of CL can be in close contact. At the same time, due to the conductivity of Ag nanoclusters can accelerate the electron transfer and the reduction peak current is thus K2S208 agent can be enhanced. Thus, enhancement of ECL intensity CdS NCs quenching and K2S208 reduction peak current can be shared with a show combined with the biological events. This detection method can sensitively detect the concentration of microRNA, the detection range of 10 fM to 1 nM., therefore, we believe that this work can be used for the development of a variety of other biological sensor.2. CdS NCs electro luminescence film in situ activation and its application in detection of H2S we propose a simple method of activation in situ, will be coated on glassy carbon electrode (GCE) on CdSNCs film (CdS NCs/GCE) containing H2O2 and citric acid soaked in the activation solution, the H2O2 as co reagent when the ECL intensity is improved about 58 times . in the process of activation, CdS NCs by H2O2 oxidation, the decrease of particle size and generate more surface defects of S; at the same time, play an important role in the stability of citric acid NCs. In addition to our ECL enhancement mechanism is discussed in detail, and the CdS NCs H2O2 in the activation of the surface excess of Cd2+ ions (S deficiency). Adsorption is the main factor, the adsorption energy of OH stable free radical H2O2 produced in the electrochemical process, so that more (CdS) - is the oxidation of the excited state, resulting in enhanced ECL signal. In addition, after the activation of nanometer crystal film becomes thinner, and the density decreased, which not only make the table the surface area increases, more exposed to S defects, and promote the diffusion of small molecule ECL detection in liquid such as reaction agent H2O2 into the membrane. Due to S (II) and CdS NCs Cd2+ combined with the effect of surface excess ion, activation of CdSNCs/GCE after immersion in Na2S solution after the letter ECL By quenching, accordingly, we use activated CdS NCs/GCE as ECL probe for detecting the concentration of Na2S, the results show that the logarithmic quenching degree the ECL signal and the Na2S concentration is linear correlation, wide linear range, 5nM-20 M, and good selectivity. Finally, we will detect this ECL probe successfully applied to the concentration of H2S in biological systems.

【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.44;TB383.1

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