Biofuel cells (BFCs) can be defined as bioelectrochemical devices responsible for the conversion of chemical energy originated from biochemical reaction into electrical energy. The conversion of energy is carry out by using enzymes and/or microorganisms as biological catalysts for the oxidation of fuels in the bioanodes (e.g. glucose) and reduction of oxidant agents in biocathodes (e.g. molecular oxygen), respectively. Some researches reports the possibility to use BFCs as implantable "biobateries", an energy conversion device for pacemaker, insulin pump, neural implants, electrical bio-stimulants and pharmacological drug-delivery. Glucose/O2 BFCs is thermodynamically very attractive due to the possibility to generate a potential difference up to 1.0V, and the presence of glucose and O2 in living organism's possibilities the development of implantable BFCs. Although BFCs are very attractive for application, enzymatic BFCs shows low kinetic constant of charge transfer between enzyme and electrode surface, and low power density and enzymatic stability. Nowadays, one of the main challenges is to improve enzymatic BFCs properties besides the possibility to develop miniaturized BFCs for application in vivo. In this context, the aim purpose of this project is to study the development of a miniaturized enzymatic glucose/O2 BFC using flexible carbon fiber (FCF) electrode. For the fabrication of bioanodes, native glucose oxidase enzyme (GOx) and deglycosylated glucose oxidase (dGOx) will be used; laccase (Lc) and bilirrubine oxidase (BOx) will be used for the obtention of biocathodes. In this case, trapping and cross-linking methodologies will be used for enzymatic immobilization. In order to improve the communication of enzyme and electrode surface, electrochemical redox mediator will be used to modify FCFs before enzymatic immobilization (e.g. methylene blue, neutral red and osmium complexes). Further, single-walled carbon nanotubes (SWCNTs) and graphene sheets (GS) will be used to improve electrical contact between enzyme and electrode surface to improve the performance of biocathodes. Finally, the miniaturization and study of the BFCs using FCFs will be one of the main focuses of this project. For this purpose, cyclic voltammetry and linear sweep voltammetry will be used to study the electrochemical behavior of FCFs modified electrodes in half-cell and unit-cell experiments.
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