Collaborative Proposal: DNA guided assembly of enzyme cascades for biocatalytic fuel cell applications

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Enzymatic fuel cells have received considerable attention because of their potential for direct conversion of abundant raw materials to electricity. The use of multi-enzyme cascades is particularly attractive as they offer the possibility of achieving a higher current density by the sequential oxidization of fuels. However, efficient substrate and electron channeling are two of the most important bottlenecks in improving the power output of multi-enzyme fuel cells. An award from the National Science Foundation Catalysis & Biocatalysis Program to Professors Wilfred Chen of the University of Delaware and Nosang Myung of the University of California-Riverside will support investigation of approaches to surmount these obstacles. The overall objective of this proposal is to investigate the use of a genetically controlled, DNA-based modular scaffold approach for the spatially-defined self-assembly of a multi-enzyme cascade for enhanced substrate and electron channeling. A simple and scalable electrospinning method will be developed to synthesize nanofiber mat electrodes with a very high surface area. A genetically designed mediator will then connect the assembly to the mat electrode. The modular nature of the proposed design allows easy alteration of spacing between the enzymes, mediators and the electrodes for investigating the optimal substrate and electron channeling in a rational manner. The unique combination of nanoengineering and bioengineering approaches will enable Chen and Myung to systematically investigate the factors affecting the overall performance of the multi-enzyme fuel cell. The initial testing of the concept will be demonstrated for the conversion of cellulose to gluconic acid, with other reactions to be studied subsequently.The proposed research is scientifically significant because the concept is built on ideas from biology extending to an entirely new engineering application. Because of the modular nature of the design, it is anticipated that the proposed framework will have a huge impact on the assembly of other multi-enzyme cascades. The proposed methodology will provide a future platform useful for the self-assembly of a wide range of multienzyme systems for fuel cell applications. From an educational perspective, graduate students participating in this research will gain an integrated perspective of the important interfaces and synergies connecting biochemistry, electrochemistry, and nanotechnology. The PIs plan outreach programs through the Mathematics Engineering Science Achievement Program at UC Riverside and the establishment of a Homeschoolers Day program in Delaware.