title: Imaging of enzyme activity by scanning electrochemical microscope equipped with a feedback control for substrate-probe distance.
abstract: The enzymatic activity of diaphorase (Dp) immobilized on a solid substrate was characterized using a scanning electrochemical microscope (SECM) with shear force feedback to control the substrate-probe distance. The shear force between the substrate and the probe was monitored with a tuning fork-type quartz crystal and used as the feedback control to set the microelectrode probe close to the substrate surface. The sensitivity and the contrast of the SECM image were improved in the constant distance mode (distance, 50 nm) with the shear force feedback compared to the image in the constant height mode without the feedback. By using this system, the SECM and topographic images of the immobilized diaphorase were simultaneously measured. The microelectrode tip used in this study was ground aslant like a syringe needle in order to obtain the shaper topographic images. This shape was also effective for avoiding the interference during the diffusion of the enzyme substrates.
authors.affiliation: Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 07 Aramaki-Aoba, 980-8579 Sendai, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Oyamatsu
authors.forename: Yu
authors.initials: Y
authors.lastname: Hirano
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kanaya
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Mase
authors.forename: Matsuhiko
authors.initials: M
authors.lastname: Nishizawa
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Matsue
mesh_terms: D004563:Electrochemistry; D004800:Enzymes, Immobilized / Q000378:metabolism; D005246:Feedback; D005486:Flavin Mononucleotide / Q000378:metabolism; D008853:Microscopy / Q000295:instrumentation / Q000379:methods*; D009245:NADH Dehydrogenase / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D004800:Enzymes, Immobilized; D005486:Flavin Mononucleotide; D009245:NADH Dehydrogenase