UNS: Enhancing charge transport in enzymatic bio-electrodes using an iron-sulfur-based synthetic electron-transport-chain

酶生物燃料电池的工作原理与所有燃料电池相同，它们使用催化剂将电子从母体分子中分离出来，并迫使电子通过导线绕过电解质屏障产生电流。酶生物燃料电池使用从活细胞中提取的酶。允许燃料电池运行的酶必须“固定”（附着）在阳极和阴极附近，才能正常工作；如果不固定，酶就会扩散到电池的燃料中，而大多数释放的电子将无法到达电极，从而影响其效率。所有基于酶的电化学装置的总体有效性取决于将酶附着在电极上的分子成功地从外部氧化点（酶活性位点）收集和运输电荷到内电极表面的能力。氧化还原酶是天然存在的传感装置，由于它们能够在酶特异性分析物存在的情况下产生电子流，因此可以作为发电厂。当这些酶被连接到电极上（活细胞外或离体），它们利用这些电子（或电）的能力会显著降低，这是由于辅酶的热力学限制（这对酶的正常运作至关重要）。常见的辅酶烟酰胺-腺嘌呤-二核苷酸（NAD）和黄素-腺嘌呤-二核苷酸（FAD）在体外具有抗循环氧化和还原能力；并且需要称为电子介质的特殊分子来帮助从辅因子中提取电子以转移到最终目标。长分子线有助于消除热力学问题，但由于电阻增加，它们本身会产生电子传递（动力学）问题。大自然已经找到了一种方法来规避与氧化还原酶相关的热力学和动力学电子传递问题，通过使用一系列独特的分子，铁硫络合物（[Fe-S]），将酶（脱酶和辅酶）络合物连接到支持表面（就像在生物电子传递链中发现的那样）。[Fe-S]配合物似乎具有促进生物系统中不受阻碍的电子传递的独特特性组合。该项目的目的是评估NAD和FAD为基础的酶系统直接连接的酶电极的反应和电子传递动力学，使用常见的硫化铁和选择[Fe-S]配合物（模拟生物电子传递链中的关键铁-硫链接）。PI将评估制造一种高效的分子线用于体外传输电子的可能性。一个主要的教育目标是通过本科课程和研究生课程将研究融入教育。学术变化研究经验（REACH）是一个项目，在这个项目中，学业上有风险的学生将与学业上成功的学生配对，并在本科项目的早期提供研究机会。PI计划评估他们早期接触实际研究是否有助于恢复他们对工程教育和学位课程的兴奋和信心。

Fernando, 1511303Enzymatic biofuel cells work on the same general principles as all fuel cells, they use a catalyst to separate electrons from a parent molecule and force it to go around an electrolyte barrier through a wire to generate an electric current. The enzymatic biofuel cell uses enzymes derived from living cells. The enzymes that allow the fuel cell to operate must be "immobilized" (attached) near the anode and cathode in order to work properly; if not immobilized, the enzymes will diffuse into the cell's fuel and most of the liberated electrons will not reach the electrodes, compromising its effectiveness. The overall effectiveness of all enzyme-based electrochemical devices is 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. Redox enzymes are naturally-occurring sensing devices that can act as power plants due to their ability to generate an electron stream in the presence of the enzyme-specific analyte. When these enzymes are wired to electrodes (outside a living cell or ex vivo), their ability to harness these electrons (or electricity) diminishes significantly due to the thermodynamic limitations associated with the coenzymes (that are essential for proper functioning of the enzyme). The common coenzymes, nicotinamide-adenine-dinucleotide (NAD) and Flavin-adinie-dinucleotide (FAD), are resistant to cyclic oxidation and reduction ex vivo; and require special molecules known as electron mediators to help extract electrons from the cofactor to transfer to the final target. Long molecular wires help eliminate the thermodynamic issue but themselves create electron transport (kinetic) issues due to increased resistance. Nature has found a way to circumvent the thermodynamic and kinetic electron transport issues associated with redox enzymes by using an array of unique molecules, the iron-sulfur complexes ([Fe-S]), to wire the enzyme (apoenzyme and coenzyme) complex to the supporting surfaces (like those found in biological electron transport chains). [Fe-S] complexes seem to have a unique combination of properties that facilitate unimpeded electron transport in biological systems.The objective of this project is to evaluate the reaction and electron transport kinetics of enzymatic electrodes of which NAD and FAD based enzyme systems are directly attached using common iron sulfides and select [Fe-S] complexes (mimicking the critical iron-sulfur link(s) in biological electron transport chains). The PI will evaluate the possibility of fabricating a highly effective molecular wire for transporting electrons ex vivo.A major educational objective is to integrate research into education via an undergraduate course and a graduate level course. Research Experience for Academic Change (REACH) is a program in which students who are academically at risk will be paired with academically successful students and provided with research opportunities early in their undergraduate program. The PI plans to evaluate whether their early exposure to practical research helps resuscitate their excitement and confidence concerning their engineering education and degree programs.