title: Adsorption and catalytic activity of glucose oxidase accumulated on OTCE upon the application of external potential.
abstract: This article describes the adsorption of glucose oxidase (GOx) onto optically transparent carbon electrodes (OTCE) under the effect of applied potential and the analysis of the enzymatic activity of the resulting GOx/OTCE substrates. In order to avoid electrochemical interferences with the enzyme redox center, control electrochemical experiments were performed using flavin adenine dinucleotide (FAD) and GOx/OTCE substrates. Then, the enzyme adsorption experiments were carried out as a function of the potential applied (ranged from the open circuit potential to +950mV), the pH solution, the concentration of enzyme, and the ionic strength on the environment. The experimental results demonstrated that an increase in the adsorbed amount of GOx on the OTCE can be achieved when the potential was applied. Although the increase in the adsorbed amount was examined as a function of the potential, a maximum enzymatic activity was observed in the GOx/OTCE substrate achieved at +800mV. These experiments suggest that although an increase in the amount of enzyme adsorbed can be obtained by the application of an external potential to the electrode, the magnitude of such potential can produce detrimental effects in the conformation of the adsorbed protein and should be carefully considered. As such, the article describes a simple and rational approach to increase the amount of enzyme adsorbed on a surface and can be applied to improve the sensitivity of a variety of biosensors.
authors.affiliation: Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, United States.
authors.forename: Tomás E
authors.initials: TE
authors.lastname: Benavidez
authors.affiliation: Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Torrente
authors.affiliation: Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, United States.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Marucho
authors.affiliation: Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, United States. Electronic address: carlos.garcia@utsa.edu.
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Garcia
mesh_terms: D000327:Adsorption; D002384:Catalysis; D003198:Computer Simulation; D004563:Electrochemistry; D005949:Glucose Oxidase / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration
chemical_list: D005949:Glucose Oxidase
keywords: Adsorption; Carbon electrode; Electrochemical; Ellipsometry; Glucose oxidase