title: Bioelectrocatalytic reduction of oxygen at gold nanoparticles modified with laccase.
abstract: To characterise bioelectrocatalytic oxygen reduction at gold nanoparticles (AuNPs) modified with Trametes hirsuta laccase (ThLc) combined electrochemical and quartz crystal microbalance measurements have been used. The electrodes with different degrees of AuNP-monolayer coverage, θ, have been studied. In every case of θ close to theoretically possible 44 ThLc molecules adsorbed at 22nm diameter AuNP. The bioelectrocatalytic current was recalculated down to the current at a single AuNP. Unexpectedly, the current at a single AuNP was higher when θ was higher. The maximum current reached at a single AuNP was 31·10(-18)A which corresponds to the enzyme turnover (kcat) 13s(-1). This rate is lower than the homogeneous ThLc turnover (190s(-1)) suggesting partial denaturation of ThLc upon adsorption or that some ThLc are not in DET contact with the electrode surface.
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, 03225 Vilnius, Lithuania.
authors.forename: Vida
authors.initials: V
authors.lastname: Krikstolaityte
authors.forename: Alejandro
authors.initials: A
authors.lastname: Barrantes
authors.forename: Arunas
authors.initials: A
authors.lastname: Ramanavicius
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnebrant
authors.forename: Sergey
authors.initials: S
authors.lastname: Shleev
authors.forename: Tautgirdas
authors.initials: T
authors.lastname: Ruzgas
mesh_terms: D000327:Adsorption; D055162:Biocatalysis; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D042845:Laccase / Q000737:chemistry* / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D055454:Trametes / Q000201:enzymology
chemical_list: D006046:Gold; D042845:Laccase; D010100:Oxygen
keywords: Bioelectrocatalytic oxygen reduction; Direct electron transfer; Gold nanoparticle; Laccase