A simple biofuel cell cathode with human red blood cells as electrocatalysts for oxygen reduction reaction

A red blood cell (RBC) from human exhibited direct electron transfer (DET) activity on a bare indium tin oxide (ITO) electrode. A formal potential of 0.152 V vs. a silver-silver chloride saturated potassium chloride (AglAgClIKCI(satd.)) was estimated for the human RBC (type AB) from a pair of redox peaks at around 0.089 and 0.215 V (vs. AglAgClIKC1(satd.)) on cyclic voltammetric (CV) measurements in a phosphate buffered saline (PBS; 39 mM; pH 7.4) solution. The results agreed well with those of a redox couple for iron-bearing heme groups in hemoglobin molecules (HbFe(1I)/HbFe(III)) on the bare ITO electrodes, indicated that DET active species were hemoglobin (Hb) molecules encapsulated by a phospholipid bilayer membrane of the human BBC. The quantity of electrochemically active Hb in the human RBC was estimated to be 30 pmol cm(-2). In addition, the human RBC exhibited oxygen reduction reaction (ORR) activity in the dioxygen (O2) saturated PBS solution at the negative potential from ca. 0.15 V (vs. AglAgClIKC1(satd.)). A single cell test proved that a biofuel cell (BFC) with an O2IRBCIITO cathode showed the open-circuit voltage (OCV) of ca. 0.43 V and the maximum power density of ca. 0.6811W cm(-2).ArticleBIOSENSORS & BIOELECTRONICS. 55:14-18 (2014)journal articl