Rational design of quinones for high power density biofuel cells† †Electronic supplementary information (ESI) available: Supplementary Fig. 1–18, supplementary Tables 1 and 2, 1H NMR and 13C NMR spectral data, HRMS (ESI), full experimental procedures, and enzymatic activity assays. See DOI: 10.1039/c5sc01538c Click here for additional data file.

Materials Unless otherwise stated, FAD-dependent glucose dehydrogenase (E.C.: 1.1.99.10, Aspergillus sp., GLDE-70-1192) was purchased from Sekisui Diagnostics (UK) and used without any further purification. For comparison experiments, GDH was also purchased from Amano Enzyme Inc., Japan (“Amano 8”, Aspergillus oryzae) and BBI Solutions USA (GLD1, Aspergillus oryzae). Bilirubin oxidase (Myrothecium sp., E.C.: 1.3.3.5) was donated by Amano Enzyme Inc., Japan. Glucose oxidase (Aspergillus niger, E.C.: 1.1.3.4, ~200 U mg) was purchased from Sigma Aldrich. Unless specified otherwise, all other chemical supplies were purchased from Sigma Aldrich. Ethylene glycol diglycidyl ether (EGDGE) was purchased from Polysciences, Inc. Toray carbon paper was purchased from Fuel Cell Earth (USA, TGP-H-060). Multi-walled carbon nanotubes (MWCNTs, -OH and –COOH modified) were purchased from Cheap Tubes. Glassy carbon working electrodes and saturated calomel reference electrodes were purchased from CH Instruments, Inc.