Biological Assembly of Enzyme Electrodes for Biofuel Cells

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1033672HuangIntellectual MeritBiofuel cells provide an environmentally benign, sustainable method for electricity production. However, the low power densities achieved to date limit their applicability. This proposed research seeks to improve the power density of biological fuel cells through controlled assembly of enzyme catalysts onto the fuel cell electrode. To achieve this goal, the proposed research seeks to improve electrical contact between the redox proteins and the conductive support, and to create electrode architectures which are designed to achieve higher power output. The assembly process is hierarchical, where proteins of nanometer dimensions are templated into viruses of nearly micron size which then self-assemble into macroscopic electrode structures. The model system will focus on glucose, a renewable feedstock, as the fuel source for electricity production. The research plan has two major objectives. The first objective is to create virus-templated enzyme electrodes which are based on assembling enzymes with inorganic constituents into an integrated structure. The heterofunctional M13 virus is designed to couple glucose oxidase to a gold nanowire through selective peptide binding to achieve mediated electron transfer between the redox center of the glucose oxidase and the electrode. The three enzyme electrode structures are proposed to overcome the limitations experienced in establishing electrical contact between the redox protein and the conductive support. The second objective is to use the liquid crystal nature of the M13 virus to self-assemble these templated enzyme electrode structures into robust electrode architectures. This approach seeks to obtain electrodes of least 10 micron thickness that are densely packed with enzymes but possess controlled porosity for electrolyte accessibility. The potential of this electrode design to achieve higher levels of power density by increasing the density of electrically-wired enzymes and ensuring accessibility of the fuel to the electrode will be assessed.Broader ImpactsThe education and outreach plan is based on the proposed research activities. Undergraduate and graduate students will receive cross-disciplinary training in bioengineering, electrochemistry, and nanomaterials. Undergraduate students from underrepresented groups will be recruited through existing programs at the University of California at Los Angeles (UCLA) to participate in the proposed research. In collaboration with California NanoSystems Institute (CNSI), biofuel cell kits and instructional videos will be developed for high school teachers as a way of bringing renewable energy topics to the high school science curriculum of the Los Angeles Unified School District.