EAGER: Iron-sulfide based Molecular-wires for Enhancing Charge Transport of Enzymatic Electrode Assemblies

1243311 Fernando智力优点：基于酶的电化学装置（如生物传感器和燃料电池）的整体有效性在很大程度上取决于将酶附着到电极上的分子的能力，以成功地从外部氧化点（酶活性位点）收集和运输电荷到内部电极表面。目前的技术使用一系列辅助分子（具有正确的辅基）将必需的电子介体和酶复合物拴在电极表面上。不幸的是，目前已知的有机束缚分子的固有低电导率使得电子传输过程受到高度限制;因此，有助于具有低功率密度的燃料电池和具有低灵敏度的传感器。缺乏一个有效的分子布线系统，可以允许不受阻碍的电荷传输是一个重大的问题，并阻碍了利用巨大的潜力生物电子器件必须提供。这项建议的总体目标是评估是否有可能取代目前的复杂的bridingsystem与一个单一的分子，有能力调解电子之间的辅酶和金属表面穿梭，并且具有正确的辅基以同时锁定在金属表面和酶复合物上。受线粒体表面发生的天然电子传递机制的启发，我们假设葡萄糖脱氢酶-烟酰胺腺嘌呤二核苷酸（GDH-NAD）脱辅基酶系统可以用合成的铁-硫[Fe-S]直接附着在金电极上配合物铁-硫复合物在真核细胞中转运葡萄糖氧化产生的电子是众所周知的。基本原理是[Fe-S]复合物的巯基将通过共价键连接到金表面上，而铁将与NAD的咪唑二嗪部分中的杂环氮原子配位，从而将脱辅基酶-辅酶复合物连接到电极上。评价通过[Fe-S]替代物将GDH-NAD+复合物拴系到金电极上的有效性。这将通过合成简单形式的[Fe-S]络合物，通过石英晶体微天平（QCM）研究评估S端结合到Au电极和Fe端结合到NAD的有效性，并通过电位和电流传感原子力显微镜（CS-AFM）研究阐明开发的电极的电流-电压（CV）行为.阐明在燃料氧化剂存在下电极表面发生的电化学现象。在葡萄糖存在下，将新型简化电极的电化学响应与传统布线电极进行比较。研究的参数将包括CV响应和燃料消耗/电极kinetics.Broader影响和EAGER基金项目的适当性：拟议的研究是高风险的，因为NAD直接附着到金属表面通过一个代理人已知作为氧化还原介体，据我们所知，从来没有尝试过。如果成功，这项研究将通过缓解阻碍有效生物电子设备发展的最复杂的瓶颈之一，对生物电子领域产生变革性的影响，受约束的电荷传输。此外，如果成功的话，这项研究将为模拟电子传输链的第一步奠定基础，这反过来又可能使我们更接近于开发已知最有效的发电厂的虚拟版本。线粒体！由于缺乏初步数据，这种性质的高风险提案不适合常规提案。然而，这种口径的潜在高回报项目是？合适吗对于渴望的人来说

1243311FernandoIntellectual Merit: The overall effectiveness of enzyme-based electrochemical devices such as biosensors and fuel cells are heavily dependent on the ability of the molecules that attach enzymes to the electrode to successfully harvest and transport charges from the outer oxidizing point (enzyme active-site) to the inner electrode surface. Current technology uses a series of ancillary molecules (with the correct prosthetic groups) to tether the essential electron mediator and the enzyme complex on to the surface of an electrode. Unfortunately, the inherently low conductivity of presently known organic tethering molecules makes the electron transport process highly constrained; therefore, contributing to fuel cells with low power density and sensors with low sensitivity. The lack of an effective molecular wiring system that can allow unimpeded charge transport is a significant problem and hinders harnessing the tremendous potential bioelectronics devices have to offer.The overall goal of this proposal is to evaluate whether it is possible to replace the current complex wiringsystem with a single molecule that has the ability to mediate electron shuttling between the coenzyme and a metal surface, and that has the correct prosthetic groups to latch simultaneously onto the metal surface and the enzyme complex.Inspired by the natural electron transport mechanism that occurs in the mitochondrial surface, we hypothesize that the glucose dehydrogenase-nicotinamide adenine dinucleotide (GDH-NAD) apoenzymecoenzyme system could be directly attached onto a gold electrode using synthetic iron-sulfur [Fe-S] complexes. Iron-sulfur complexes are well known to transport electrons generated by glucose oxidation in eukaryotic cells. The rationale is that the thiol groups of the [Fe-S] complex would attach onto the gold surface via covalent linkages while iron will coordinate with heterocyclic nitrogen atoms in imidazolediazine moieties of NAD attaching the apoenzyme-coenzyme complex on to the electrode.The hypothesis will be tested via the following Specific Objectives:1. Evaluate the effectiveness of tethering GDH-NAD+ complex onto a gold electrode via [Fe-S]surrogates. This will be done by synthesizing simple forms of [Fe-S] complexes, evaluating theeffectiveness of binding the S end onto the Au electrode and the Fe end to the NAD viaquartz crystal microbalance (QCM) studies, and elucidating the current-voltage (CV) behaviorof a developed electrode via potentiometric and current sensing atomic force microscopy(CS-AFM) studies.2. Elucidate electrochemical phenomena occurring at the electrode surface in the presence of thefuel oxidant. The electrochemical response of the novel simplified electrode will be compared with theconventionally wired electrode in the presence of glucose. The parameters studied willinclude CV response and fuel-consumption/electrode kinetics.Broader Impacts and the Appropriateness of the Project for EAGER Funding:The proposed research is high-risk since direct attachment of NAD to a metal surface via a surrogateknown to act as a redox mediator, to the best of our knowledge, has never been attempted before. Ifsuccessful, the research will provide a transformative impact on the bioelectronics area by alleviating oneof the most intricate bottlenecks impeding development of effective bio-electronic devices, i.e.,constrained charge transport. Moreover, if successful, this research will lay the foundation for mimickingthe first step of the electron transport chain which in turn may take us a step closer to developing asynthetic version of the most effective power plant known ?mitochondria!A high-risk proposition of this nature will not fit into a regular proposal due to lack of preliminary data.However, a potentially high-payoff project of this caliber is a ?good fit? for an EAGER