A novel enzyme-immobilization method for a biofuel cell

Biofuel cells utilizing biocatalysts are attractive alternatives to metal catalyst-based cells because of environmentally friendly cells and their renewability and good operations at room temperatures, even though they provide a low level of electrical power. In this study, the effect of a novel enzyme immobilization method on anodic electrical properties was evaluated under ambient conditions for increasing the power of an enzyme-based biofuel cell. The anodic system employed in the cell contained a gold electrode, pyrroloquinoline quinone (PQQ) as the electron transfer mediator, lactate dehydrogenase (LDH), β-nicotinamide adenine dinucleotide (NAD⁺) as the cofactor, and lactate as the substrate. The anodic electrical properties increased as a result of the novel enzyme-immobilization method. Furthermore, lactate, NAD⁺, or CaCl₂, which can all influence enzyme activation, were used to prevent covalent bond formation near the active site of the LDH during enzyme-immobilization. Protection of the active site of the LDH using this novel enzyme-immobilization method increased its stability, which enabled to increase power production (142 μW/cm²) in a basic enzymatic fuel cell (EFC).