发展新型电致化学发光透明生物传感器

The use of a transparent electrode in electrogenerated chemiluminescence (ECL) may be beneficial to a higher sensitivity and make the configuration design of the electrochemical cell more flexible, for example, the light emission can be transmitted through the electrode to the detector, avoiding the interference from the absorbing species in solution and the matrix effect of the analysis system. Due to its high efficiency, the Ru(bpy)32+ (bpy = 2,2´-bipyridine)/tri-n-propylamine (TPrA) system is most commonly used. It was found recently that efficient light emission can be produced at an oxidation potential well before the oxidation of Ru(bpy)32+. The new type of ECL, named here as low-oxidation-potential (LOP) ECL, follows a unique mechanism where the oxidation of the luminophor molecule is not required and, therefore, exhibit several advantages over the conventional ECL method, such as low oxidation potential, higher sensitivity, and spatial control of TPrA oxidation and Ru(bpy)32+ emission. This project will develop a transparent biosensor based on the LOP ECL. A transparent network film of gold or copper-gold core-shell nanowires will be fabricated. While the gold surface will be modified by fluorosurfactant FSN which facilitates TPrA oxidation, the Ru(bpy)32+ emitter will be bridge-linked to the glass of the open area of network. In the conventional ECL detection, since the oxidation of Ru(bpy)32+ is necessary, the emitters are usually directly immobilized on the electrode surface. The disadvantages associated with this conventional method are obvious. Firstly, the immobilized emitter molecules would occupy a lot of electrode active sites. This may significantly suppress co-reactant oxidation which plays an important role in the ECL process and, therefore, the emission intensity would be reduced, leading to a lower sensitivity. Secondly, during the ECL detection, it requires an electrode potential more positive than 1.26 V vs. NHE to oxidize Ru(bpy)32+, which would probably destroy the covalent bond between the attached Ru(bpy)32+ and the electrode. Thirdly, the electrode may quench the emission of Ru(bpy)32+ to some extent. For the mechanism study, the transparent network electrode will allow various in situ spectroscopies to investigate the LOP ECL leading to a better understanding of the new features of the LOP ECL. On the basis of above studies, a new class of transparent biosensors employing the LOP ECL signal for DNA probe will be developed.

在电致化学发光（ECL）中应用透明电极可使得检测光信号直接透过电极传递到检测装置，避免溶液物种的干扰，提高检测的灵敏度。该项目将发展一种基于三联吡啶钌（发光分子）/三正丙胺（共反应剂）体系低氧化电位（LOP）发光途径的新型ECL透明传感器。LOP ECL无需氧化发光分子，相对于传统ECL可在更低的氧化电位获得更强的检测信号。构建基于金纳米线或铜(核)-金(壳)纳米线的透明网络电极，通过全氟表面活性剂对金表面进行修饰，促进溶液中三正丙胺的快速氧化；将三联吡啶钌固定在网络电极的空白玻璃上，克服传统ECL检测中发光分子直接吸附在电极上的诸多缺点，如抑制三正丙胺的氧化，氧化过程对桥接基团的破坏，以及导电基底对三联吡啶钌发光的淬灭效应。利用网络电极透明性的优点，结合各种原位谱学技术深入研究LOP ECL的过程和机理。将该电极体系进一步应用于DNA的杂化测序分析，发展新型ECL透明生物传感器。

电致化学发光（ECL）由电极反应引发特异性化学发光反应，是化学发光方法与电化学方法相结合的产物，在生化、临床和环境分析等方面独具特色。三联吡啶钌（Ru(bpy)32+）/脂肪胺（如三正丙胺TPrA）是广泛应用的一种ECL检测体系。该体系可通过多种不同的反应途径发光，其中低氧化电位（LOP）ECL无需氧化发光分子Ru(bpy)32+，相对于传统ECL，LOP ECL可在更低的电位进行发光检测。在该项目研究中，我们通过离子强度和pH调控，利用全氟表面活性剂对电极进行修饰，和选择合适的共反应剂脂肪胺等多种方法提高了ECL特别是LOP ECL分析的灵敏度；机理研究表明脂肪胺阳离子自由基的寿命是影响ECL发光效率的关键因素，加深了对ECL特别是LOP ECL发光过程的认识。在具体分析检测方面，我们通过全氟表面活性剂修饰的金电极实现了对半胱氨酸（CySH）和同型半胱氨酸（HCy）等生物小分子的选择性电分析检测。该修饰电极具有制备方法简单，成本低，对CySH和HCy的分辨能力好以及抗干扰性强等优点。我们发现碘离子和全氟表面活性剂在金电极表面具有相似的电化学吸脱附行为，在此基础上我们制备了碘包覆的金纳米颗粒，该纳米颗粒对含巯基氨基酸和多肽分子具有选择性的光谱响应，从而为这些生物分子的比色检测提供了可能。另外，磁性纳米材料在生物技术如载药和免疫分析，磁共振成像，以及标的物的吸附分离等领域都有着重要的应用。我们制备了碳包覆的磁性纳米复合材料，成功地通过控制煅烧温度、气体流速、煅烧时间和升温速率等方法对材料的磁性进行调控，全面揭示了材料制备过程中影响磁性大小的各种因素。.我们还开展了水分解制备氢气的电催化研究，发展了多种基于廉价过渡金属的水氧化（如基于铜纳米线网络的水氧化透明催化电极）和水还原电催化剂和基于银离子的氯离子氧化（用作水氧化替代半反应）电催化剂。这些催化剂电极除了在水分解相关半反应中起着重要作用，在ECL反应中也可能具有潜在的应用价值，如催化ECL共反应剂脂肪胺在更低的电位氧化等，从而提高ECL检测的灵敏度和选择性。