Biofuel cell design

ELECTRICAL CONTACT OF REDOX ENZYMES WITH ELECTRODES FOR AMPEROMETRIC BIOSENSING AND BIOFUEL CELL DESIGN... 

RECONSTITUTED ENZYME-ELECTRODES FOR BIOFUEL CELL DESIGN... 

Fig. 3.1 Schematic representation of an enzymatic biofuel cell design based on the electrical connection of a laccase at the cathode and glucose oxidase at the anode...

The scientific challenge of these enzymatic biofuel cells is to develop devices with compatible power and size to use them as power sources for portable devices such as GPS, mobile phone, MP3 players, or mobile computers. A steady increasing interest within enzymatic biofuel cell design is dedicated to the production of electrical energy from the electro-enzymatic degradation of glucose and O2. These... 

Guven G, Prodanovic R, Schwaneberg U. Protein engineering - an option for enzymatic biofuel cell design. Electroanalysis 2010 22 765-775. 

Rincon RA, Lau C, Luckarifl HR, Garcia KE, Adkins E, Johnson GR, Atanassov P. Enzymatic fuel cells integrating flow-through anode and air-breathing cathode into a membrane-less biofuel cell design. Biosens Bioelectron 2011 27 132 136. 

Kerzenmacher S, Mutschler K, Kraehng U, Baumer H, Ducree J, Zengerle R, von Stetten F. A complete testing environment for the automated parallel performance characterization of biofuel cells design, validation, and application. J Appl Electrochem... 

Fuel cells based on unmediated electrocatalysis by heme-containing sugar dehydrogenases have not yet been tested in biological fluids, but may be useful for implantable applications, as they avoid the need for toxic or expensive mediators and have minimal design constraints. Realistically, the lifetime of biofuel cells is still insufficient for biomedical applications requiring surgical installation. 

The design of biocatalytic electrodes for activity toward gaseous substrates, such as dioxygen or hydrogen, requires special consideration. An optimal electrode must balance transport in three different phases, namely, the gaseous phase (the source of substrate), the aqueous phase (where the product water is released and ionic transport takes place), and the solid phase (where electronic transport occurs). Whereas the selectivity of biocatalysts facilitates membraneless cells for implementation in biological systems that provide an ambient electrolyte, gas-diffusion biofuel cells require an electro-... 

Bioelectrocatalysis involves the coupling of redox enzymes with electrochemical reactions [44]. Thus, oxidizing enzymes can be incorporated into redox systems applied in bioreactors, biosensors and biofuel cells. While biosensors and enzyme electrodes are not synthetic systems, they are, essentially, biocatalytic in nature (Scheme 3.5) and are therefore worthy of mention here. Oxidases are frequently used as the biological agent in biosensors, in combinations designed to detect specific target molecules. Enzyme electrodes are possibly one of the more common applications of oxidase biocatalysts. Enzymes such as glucose oxidase or cholesterol oxidase can be combined with a peroxidase such as horseradish peroxidase. 

In addition, metal BC can be combined with enzymes immobilized in the membranes for the design of biosensors and biofuel cells [58,59]. 

The main potential of mediated ET lies in the increase of current densities, as the essential challenge of designing biofuel cells is to increase the biocatalytic power of these devices. Biofuel cells presently reach a power output in the range of about 10 to 10 Wcm . Practical conventional fuel cells operate in the range of about 1 to 10 Wcm [303]. Taking the calculations from Barton and coworkers into consideration [70], in which, as mentioned above, the theoretical current density of a monolayer was estimated to be about SOpAcm" one would require thousands of layers to obtain a current density above 10 mA cm f... 

It should also be emphasized the ecological aspects inherent to biofuel cells that contrarily to fuel cells, require no metal catalysts (platinum, nickel, palladium, rhodium, iridium, etc.). Indeed, materials, fuels, and products used in the design of all biofuel cells are biodegradable. Consequently, these biofuel cells are not subjected to major economic issues related to metal catalyst. Indeed, the increasing demand for strategic metals and metal alloys by high-tech industries, aerospace or automotive industry causes a process of depletion of these materials. 

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