An intravenous implantable glucose/dioxygen hybrid enzyme–Pt micro-biofuel cell (BFC) was investigated. In this miniaturized BFC, a flexible carbon fiber (FCF) microelectrode modified with neutral red redox mediator and glucose oxidase was used as the bioanode, and an FCF modified with platinum nanoparticles stabilized on PAMAM-G4 dendrimer was used as the cathode. In vitro experiments conducted using the BFC in a phosphate buffer solution (50 mmol L−1, pH = 7.2) and glucose (47 mmol L−1) showed high electrocatalytic performance with an open circuit voltage (OCV) of 400 mV, a maximum current density of 2700 μA cm−2 at 0.0 V and a maximum output power of 200 μW cm−2 at 250 mV. Under physiological conditions, glucose from rat blood is used as a fuel in anodic reactions and dissolved molecular oxygen is used as the oxidizing agent on the cathode. For in vivo experiments, the BFC was inserted into the jugular vein of a living rat (Rattus novergicus) using a catheter (internal diameter 0.5 mm). The power density of the implantable BFC was evaluated over a period of 24 h, and an OCV of 125 mV with a maximum power density of 95 μW cm−2 was obtained at 80 mV.
