title: Bioelectrochemical studies of azurin and laccase confined in three-dimensional chips based on gold-modified nano-/microstructured silicon.
abstract: Double-sided three-dimensional porous silicon chips, 6 mm x 6 mm, covered with a 40 nm gold (nano)layer, were fabricated from a porous silicon wafer. Scanning electron microscopy along with electrochemical characterisation showed sample conductivity, mechanical stability, and high surface area of the thus fabricated devices, viz. 10 times higher electrochemically active surface area compared to the geometric area. The three-dimensional gold coated silicon chips were further modified with thiol layers, followed by immobilisation of a simple copper-containing redox protein, azurin, or a complex multicopper redox enzyme, laccase. The bioelectrochemical studies showed very high surface concentrations of azurin and laccase, i.e. close to the theoretical monolayer coverage. However, direct electron transfer reactions between the biomolecules and gold surfaces were observed only for a small percentage of the immobilised redox protein and enzyme, respectively. Thus, highly efficient oxygen-bioelectroreduction on laccase-modified 3D thiol-gold-porous silicon chips (as compared to planar laccase-modified gold electrodes, 42 microA/cm(2)vs. 7 microA/cm(2), respectively) was obtained only in the presence of an efficient soluble redox mediator.
authors.affiliation: Department of Physics, University of Aarhus, Aarhus, Denmark.
authors.forename: Anton
authors.initials: A
authors.lastname: Ressine
authors.forename: Cristina
authors.initials: C
authors.lastname: Vaz-Domínguez
authors.forename: Victor M
authors.initials: VM
authors.lastname: Fernandez
authors.forename: Antonio L
authors.initials: AL
authors.lastname: De Lacey
authors.forename: Thomas
authors.initials: T
authors.lastname: Laurell
authors.forename: Tautgirdas
authors.initials: T
authors.lastname: Ruzgas
authors.forename: Sergey
authors.initials: S
authors.lastname: Shleev
mesh_terms: D001400:Azurin / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry*; D040081:Protein Array Analysis / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*
chemical_list: D001400:Azurin; D006046:Gold; D042845:Laccase; D012825:Silicon