title: Polymer-based protein engineering grown ferrocene-containing redox polymers improve current generation in an enzymatic biofuel cell.
abstract: Enzymatic biofuel cells (EBFCs) are capable of generating electricity from physiologically present fuels making them promising power sources for the future of implantable devices. The potential application of such systems is limited, however, by inefficient current generation. Polymer-based protein engineering (PBPE) offers a unique method to tailor enzyme function through tunable modification of the enzyme surface with functional polymers. In this study, we report on the modification of glucose oxidase (GOX) with ferrocene-containing redox polymers to increase current generation efficiency in an enzyme-modified anode. Poly(N-(3-dimethyl(ferrocenyl)methylammonium bromide)propyl acrylamide) (pFcAc) was grown from covalently attached, water-soluble initiator molecules on the surface of GOX in a "grafting-from" approach using atom transfer radical polymerization (ATRP). The covalently-coupled ferrocene-containing polymers on the enzyme surface promoted the effective "wiring" of the GOX active site to an external electrode. The resulting GOX-pFcAc conjugates generated over an order of magnitude increase in current generation efficiency and a 4-fold increase in maximum EBFC power density (≈1.7µWcm(-2)) with similar open circuit voltage (0.27V) compared to native GOX when physically adsorbed onto paddle-shaped electrodes made up of electrospun polyacrylonitrile fibers coated with gold nanoparticles and multi-wall carbon nanotubes. The formation of electroactive enzyme-redox polymer conjugates using PBPE represents a powerful new tool for the improvement of mediated enzyme-based bioelectronics without the need for free redox mediators or anode/cathode compartmentalization.
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. Electronic address: ascampbe@andrew.cmu.edu.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Campbell
authors.affiliation: Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Disruptive Health Technology Institute, Carnegie Mellon University, Pittsburgh, PA, USA. Electronic address: hiromura@andrew.cmu.edu.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Murata
authors.affiliation: Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Disruptive Health Technology Institute, Carnegie Mellon University, Pittsburgh, PA, USA. Electronic address: scarmali@andrew.cmu.edu.
authors.forename: Sheiliza
authors.initials: S
authors.lastname: Carmali
authors.affiliation: Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA; Institute of Polymer and Dye Technology, Lodz University of Technology, Stefanowskiego 12/16, 90-924 Lodz, Poland. Electronic address: km3b@andrew.cmu.edu.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Matyjaszewski
authors.affiliation: Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Department of Materials Science & Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. Electronic address: mohammad@cmu.edu.
authors.forename: Mohammad F
authors.initials: MF
authors.lastname: Islam
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Center for Polymer-based Protein Engineering, Carnegie Mellon University, Pittsburgh, PA, USA; Disruptive Health Technology Institute, Carnegie Mellon University, Pittsburgh, PA, USA; Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA. Electronic address: alanrussell@cmu.edu.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Russell
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D001234:Aspergillus niger / Q000201:enzymology*; D001674:Bioelectric Energy Sources / Q000382:microbiology; D004560:Electricity; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D005949:Glucose Oxidase / Q000737:chemistry*; D000075163:Metallocenes; D010084:Oxidation-Reduction; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D005296:Ferrous Compounds; D000075163:Metallocenes; D011108:Polymers; D005949:Glucose Oxidase; C004998:ferrocene
keywords: ATRP; Biofuel cell; Ferrocene; Glucose oxidase; Polymer-based protein engineering; Redox polymer