The fructose/dioxygen biofuel cell, one of the direct electron transfer (DET)-type bioelectrochemical devices, utilizes fructose dehydrogenase (FDH) on the anode and multi-copper oxidase such as bilirubin oxidase (BOD) on the cathode as catalysts. The power density in the literature is limited by the biocathode performance. We show that the DET-type biocathode performance is greatly improved, when bilirubin or some related substances are adsorbed on electrodes before the BOD adsorption. Several data show that the substrate modification induces the appropriate orientation of BOD on the electrode surface for the DET. The substrate-modification method has successfully been applied to air-breathing gas-diffusion-type biocathodes. We have also optimized the conditions of the FDH adsorption on carbon cryogel electrodes. Finally, a one-compartment DET-type biofuel cell without separators has been constructed, and the maximum power density of 2.6 mW cm(-2) was achieved at 0.46 V of cell voltage under quiescent (passive) and air atmospheric conditions.

This study showed that cystatin C is a marker of inflammation as well as renal function.

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The current density of gas-diffusion biocathodes for the oxygen reduction in biofuel cells was successfully increased by adjusting the hydrophobicity of porous carbon electrodes and by adding small amount of non-ionic surfactant to enzyme solution to be used in the enzyme adsorption process. Optimization of the hydrophobicity was performed with non-glycoprotein cupper efflux oxidase as an electrocatalyst. Carbon slurry was prepared by mixing Ketjen black and polytetrafluoroethylene in 2-propanol at a weight ratio of 3:2. Carbon paper was modified with the slurry and dried at 60°C to remove the solvent. Addition of small amount of non-ionic surfactant such as Triton X-100 (about 0.01%) into the enzyme solution was very effective to adsorb the enzyme on the hydrophobic porous carbon surface. The proposed method is also effective for glycoprotein multi-copper oxidase to fabricate high performance gas-diffusion biocathode.