Selenide-based electrocatalytic sensors for sensitive peroxynitrite detection in biological media: a bottom-up approach for functional interface design

项目摘要： 背景和挑战：过氧亚硝酸盐（OONO-）作为一种有效的细胞毒性化合物出现， 与一系列病理生理状况有关过氧亚硝酸盐是主要的产品， 一氧化氮和超氧阴离子自由基体内反应。这种多方面的生理反应 化合物直接涉及许多病理学，包括心血管疾病、免疫性疾病、 反应，慢性炎症和败血症，仅举几例。根据美国《金融时报》最近的统计， 根据美国心脏协会的数据，仅心血管疾病就意味着每4分钟就有7人死亡。另 另一方面，败血症每年影响美国170万成年人，并可能导致更多的人死亡。 超过25万人死亡。仅仅这两个统计数据就令人震惊， 生物分析物是一个重要的优先事项。将过氧亚硝酸盐与所有引用的病理联系起来的共同线索 它对大多数细胞成分，包括DNA、蛋白质和细胞中的脂质， 膜。蛋白质、DNA和脂质的大量氧化和其他转化有助于 关键细胞功能的破坏。 评估过氧亚硝酸盐的有害影响并检查其潜在信号作用的假设 如果不首先精确地测量和监测其浓度，就无法实现。这个任务 然而，由于在生理条件下低的亚微摩尔浓度， 它的高反应性。为了阐明过氧亚硝酸盐的重要性， 这种代谢物的病理生理作用一些已知的检测方法， 过氧亚硝酸盐包括氧化荧光探针，EPR光谱，化学发光， 免疫组织化学和探针硝化;然而，这些更难以应用于实时 由于其固有的复杂性，过亚硝酸根的电化学检测是一种简单的 和更方便的技术应用于生物环境。然而，一个系统的发展 缺乏合适的电极界面来提高这种分子的灵敏度和选择性。 近年来，合成了几种有机硒化物作为抗氧化剂应用于药物化学。 电化学数据表明，某些有机硒化合物具有特定的氧化还原特性， 在溶液中与过氧亚硝酸根的活性。由于这些原因，我们认为， 与有机硒化合物连接到表面将潜在地作为介导PON的催化实体 电催化测定 我们的建议：在这项工作中，我们建议开发一种功能薄膜材料， 有机硒化合物化学附着在石墨电极上，并使用该界面进行灵敏的 过氧亚硝酸根的电化学测定这种自下而上的界面设计方法是创新的 因为它允许我们设计一个电催化界面，用于检测和确定 过氧亚硝酸盐由所使用的有机硒化物的分子和电子性质驱动。这是由 总的假设是，富含氧化还原的有机硒化合物将允许我们将它们用作活性物质， 连接到电极表面的氧化还原催化中心以电催化测量溶液中的PON。 本论文的主要工作包括以下三个方面：1）研究硒化物修饰的PON电极 使用参比化合物进行测定，然后2）生成具有不同的硒化物的文库， 在硒催化中心上的取代基，并测试所得改性的催化性能。 最后3）选择性能最好的催化界面 通过将该过程转移到超微电极（碳纤维）来制备单体无源光网络 微传感器，用于生物环境下。意义：成功研制出可靠的 PON微传感器不仅能够在生物学条件下原位测量这种反应性应力标记物， 但也将揭示这种强大物种在环境中运作的模糊机制， 许多疾病状态。

Project Summary: Background and Challenge: Peroxynitrite (OONO-) emerged as a potent cytotoxic compound and has been implicated in a host of pathophysiological conditions. Peroxynitrite is the primary product of the in vivo reaction of nitric oxide and superoxide anion-radical. The multifaceted physiologic reactions of this compound are directly implicated in a number of pathologies including cardiovascular disease, immune response, chronic inflammation, and sepsis, to cite a few. According to recent statistics by the American Heart Association, just cardiovascular disease alone claims about 7 deaths every 4 minutes. On the other hand, sepsis affects 1.7 million adults in the United States each year and potentially contributes to more than 250,000 deaths. Just these two statistics are staggering and make the footprint of this deadly biological analyte an important priority. The common thread that links peroxynitrite to all cited pathologies is its potent reactivity toward most cellular components including DNA, proteins, and lipids in cell membranes. Substantial oxidations and other transformations of proteins, DNA, and lipids contribute to the disruption of key cellular functions. Assessing peroxynitrite’s deleterious effects and examining hypotheses of its potential signaling roles cannot be achieved without first accurately measuring and monitoring its concentration. This task is however inherently difficult due to low submicromolar concentrations under physiologic conditions coupled with its high reactivity. Sensitive and accurate measurement of peroxynitrite is crucial in order to shed light on the illusive pathophysiologic roles of this metabolite. Some of the known detection methods for peroxynitrite include oxidation of fluorescent probes, EPR spectroscopy, chemiluminescence, immunohistochemistry, and probe nitration; however, these are more difficult to apply for real-time quantification due to their inherent complexity. The electrochemical detection of peroxynitrite is a simpler and more convenient technique for application in biological settings. However, a systematic development of the right electrode interface that enhances the sensitivity and selectivity for this molecule is lacking. Recently, several synthetic organic selenides have been prepared as antioxidants in medicinal chemistry. Electrochemical data in our hands showed that some organoselenium compounds have specific redox activity with peroxynitrite in solution. For these reasons, we believe that an electrode interface decorated with organoselenides attached to the surface will potentially serve as catalytic entities for mediated PON electrocatalytic determination. Our proposal: In this work, we propose to develop a functional thin film material based on defined organic selenides chemically attached on graphite electrodes and use this interface in sensitive electrochemical determination of peroxynitrite. This bottom-up interface design approach is innovative because it allows us to design an electrocatalytic interface for the detection and determination of peroxynitrite driven by molecular and electronic properties of the organic selenides used. This is driven by the overall hypothesis that the redox-rich organoselenium compounds will allow us to use them as active redox catalytic centers tethered to the electrode surface to electrocatalytically measure PON in solution. The work will pursue three specific aims including: 1) developing a selenide-decorated electrode for PON determination using a reference compound, followed by 2) generating a library of selenides with varying substituents on the selenium catalytic center and test the catalytic properties of the resulting modified interface towards PON determination; and finally 3) miniaturizing the best performing catalytic interfaces by transferring the process to ultramicroelectrodes (carbon fiber) to prepare a single-body PON microsensor for use under biological settings. Significance: The successful development of a reliable PON microsensor will not only enable in-situ measurement of this reactive stress marker under biological setting but will also shed light on obscure mechanisms through which this potent species operates under many disease states.