SBIR Phase I: High-Power and High-Energy-Density Enzymatic Fuel Cell through an In Vitro Synthetic Enzymatic Pathway

这个小企业创新研究一期项目将开发高功率和高能量密度的酶燃料电池（EFC），可以完全氧化低成本的麦芽糊精（即，部分水解的淀粉片段）。EFC作为下一代环境友好型（微型）电源受到越来越多的关注。与微生物燃料电池相比，EFC具有更高的功率密度，适用于更多的应用。然而，目前的EFC受到己糖分子被一种或两种氧化还原酶（即，2-4每摩尔葡萄糖产生1摩尔电子）和短的酶寿命。该项目的目标是通过正在申请专利的合成酶途径证明EFCs中麦芽糊精完全氧化的技术可行性。该项目的技术创新是通过组装热稳定酶来构建无ATP和无CoA的途径，以产生每个葡萄糖单位24个电子并增加功率密度。因此，由于燃料的完全氧化，预计EFC将具有高能量密度，由于级联酶之间的底物通道和减轻酶的产物抑制而具有高功率密度，以及由于使用热稳定酶而具有长寿命。该项目更广泛的影响/商业潜力是开发具有四个吸引人的优点的生物启发糖生物电池：（i）生物降解性，（ii）安全性，（iii）高能量存储密度（例如，400 Wh电/kg，几乎是锂离子电池的三倍），和（iv）通过添加糖溶液快速再填充。EFC将具有广泛的潜在应用，例如可充电电池充电器（例如，用于户外用途或便携式军事设备的蜂窝电话充电器）、教育玩具套件和一次性（原）电池。在未来，小型化的糖动力EFC可能会取代一些二次（可充电）电池。除了电极和电线之外，糖动力的EFC几乎是100%可生物降解的，并且基于无毒和地球丰富的元素。麦芽糖糊精溶液既不有毒也不易燃。配备有这种体外合成途径的EFC的创新将极大地促进体外合成生物学的概念，并表现出另一个优势，即主要由于缺乏细胞膜而比微生物更快的反应速率。此外，用可再生和低成本的糖，即麦芽糊精或未来的纤维素材料发电，将减少温室气体排放，提高国家能源安全，促进农村经济。

This Small Business Innovation Research Phase I project will develop high-power and high-energy-density enzymatic fuel cells (EFCs) that can completely oxidize low-cost maltodextrin (i.e., a partially hydrolyzed starch fragment). EFCs have received increasing interest as a next-generation, environmentally friendly (micro-)power source. Compared to microbial fuel cells, EFCs have much higher power densities suitable for more applications. However, current EFCs are limited by the partial oxidization of hexose molecules by one or two redox enzymes (i.e., 2-4 mol of electrons produced per mol of glucose) and a short enzyme lifetime. The goal of this project is to demonstrate the technical feasibility of the complete oxidation of maltodextrin in EFCs through a patent-pending synthetic enzymatic pathway. The technological innovation of this project is the construction of an ATP-free and CoA-free pathway by an assembly of thermostable enzymes to generate 24 electrons per glucose unit and increase power density. As a result, EFCs are expected to feature high energy density due to the complete oxidization of the fuel, high-power density due to substrate channeling among cascade enzymes and the mitigation of product inhibition of the enzymes, and a long lifetime due to the use of thermostable enzymes.The broader impact/commercial potential of this project is developing bio-inspired sugar biobatteries featuring four appealing advantages: (i) biodegradability, (ii) safety, (iii) high energy storage density (e.g., 400 Wh electricity/kg for a 20% (w/v) maltodextrin solution, nearly three times that of lithium ion batteries), and (iv) fast refilling by adding a sugar solution. EFCs would have broad potential applications, such as rechargeable battery chargers (e.g., cellular phone chargers for outdoor uses or portable military devices), educational toy kits, and disposable (primary) batteries. In the future, miniaturized sugar-powered EFCs could potentially replace some secondary (rechargeable) batteries. Sugar-powered EFCs would be nearly 100% biodegradable, with the exception of the electrodes and wires, and are based on non-toxic and earth-abundant elements. The maltodextrin solution is neither toxic nor flammable. The innovation of EFCs equipped with this in vitro synthetic pathway would greatly promote the concept of in vitro synthetic biology and demonstrate another advantage a faster reaction rate than that of microbes due primarily to the absence of a cellular membrane. In addition, the generation of electricity from renewable and low-cost sugars, namely maltodextrin or future cellulosic materials, would decrease greenhouse gas emissions, increase national energy security, and promote rural economies.