title: Electrochemical Characterization of Layer-By-Layer Assembled Ferrocene-Modified Linear Poly(ethylenimine)/Enzyme Bioanodes for Glucose Sensor and Biofuel Cell Applications.
abstract: Ferrocenylhexyl- and ferrocenylpropyl-modified linear poly(ethylenimine) (Fc-C6-LPEI, Fc-C3-LPEI) were used with periodate-modified glucose oxidase (p-GOX) in the layer-by-layer assembly of enzymatic bioanodes on gold. Fc-C6-LPEI/p-GOX and Fc-C3-LPEI/p-GOX films of 16 bilayers were capable of generating up to 381 ± 3 and 1417 ± 63 μA cm(-2), respectively, in response to glucose. These responses are greater than those of analogous bioanodes fabricated using conventional cross-linking techniques and are extremely high for planar, low surface area, single-enzyme electrodes. (Fc-C3-LPEI/p-GOX)8 films generated 86 ± 3 μW cm(-2) at pH 7.0 and 149 ± 7 μW cm(-2) at pH 5.0, when poised against an air-breathing platinum cathode in a compartment-less biofuel cell. An increase in power output with decreasing pH was shown to be a result of increases in the platinum cathode performance, indicating it is the rate-limiting electrode in the biofuel cells. The effect of fabrication wash time on the buildup of material at the electrode's surface was probed using cyclic voltammetry (CV) and constant potential amperometry. The use of electrochemical techniques as a diagnostic tool for studying the material deposition process is discussed. CV peak separation (ΔE), surface coverage of the electroactive ferrocene (ΓFc), and amperometric sensitivity of the enzyme to glucose (Jmax), studied as a function of numbers of bilayers, showed that physisorption of materials onto the surface results from initial patchy deposition, rather than in distinctly uniform layers.
authors.affiliation: Department of Chemistry and Biochemistry, ‡University of Oklahoma Biomedical Engineering Center, and §School of Chemical, Biological and Materials Engineering, The University of Oklahoma , 100 East Boyd, Norman, Oklahoma 73019, United States.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Godman
authors.affiliation: Department of Chemistry and Biochemistry, ‡University of Oklahoma Biomedical Engineering Center, and §School of Chemical, Biological and Materials Engineering, The University of Oklahoma , 100 East Boyd, Norman, Oklahoma 73019, United States.
authors.forename: Jared L
authors.initials: JL
authors.lastname: DeLuca
authors.affiliation: Department of Chemistry and Biochemistry, ‡University of Oklahoma Biomedical Engineering Center, and §School of Chemical, Biological and Materials Engineering, The University of Oklahoma , 100 East Boyd, Norman, Oklahoma 73019, United States.
authors.forename: Sean R
authors.initials: SR
authors.lastname: McCollum
authors.affiliation: Department of Chemistry and Biochemistry, ‡University of Oklahoma Biomedical Engineering Center, and §School of Chemical, Biological and Materials Engineering, The University of Oklahoma , 100 East Boyd, Norman, Oklahoma 73019, United States.
authors.forename: David W
authors.initials: DW
authors.lastname: Schmidtke
authors.affiliation: Department of Chemistry and Biochemistry, ‡University of Oklahoma Biomedical Engineering Center, and §School of Chemical, Biological and Materials Engineering, The University of Oklahoma , 100 East Boyd, Norman, Oklahoma 73019, United States.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Glatzhofer
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D001674:Bioelectric Energy Sources; D015374:Biosensing Techniques / Q000295:instrumentation*; D055664:Electrochemical Techniques; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000737:chemistry*; D006046:Gold; D000075163:Metallocenes; D011094:Polyethyleneimine / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D005296:Ferrous Compounds; D000075163:Metallocenes; D006046:Gold; D011094:Polyethyleneimine; D005949:Glucose Oxidase; D005947:Glucose; C004998:ferrocene