title: Adsorption-penetration studies of glucose oxidase into phospholipid monolayers at the 1,2-dichloroethane/water interface.
abstract: The interaction between glucose oxidase (GOx) and phospholipid monolayers is studied at the 1,2-dichloroethane/water interface by electrochemical impedance spectroscopy. Electrochemical experiments show that the presence of GOx induces changes in the capacitance curves at both negative and positive potentials, which are successfully explained by a theoretical model based on the solution of the Poisson-Boltzmann equation. These changes are ascribed to a reduced partition coefficient of GOx and an increase of the permittivity of the lipid hydrocarbon domain. Our results show that the presence of lipid molecules enhances the adsorption of GOx molecules at the liquid/liquid interface. At low lipid concentrations, the adsorption of GOx is probably the first step preceding its penetration into the lipid monolayer. The experimental results indicate that GOx penetrates better and forms more stable monolayers for lipids with longer hydrophobic tails. At high GOx concentrations, the formation of multilayers is observed. The phenomenon described here is strongly dependent on 1) the GOx and lipid concentrations, 2) the nature of the lipid, and 3) the potential drop across the interface.
authors.affiliation: Laboratory of Physical Chemistry and Electrochemistry, Department of Chemical Technology, Helsinki University of Technology, P.O. Box 6100, Kemistintie 1, 02015 HUT Espoo, Finland. helder.santos@hut.fi
authors.forename: Hélder A
authors.initials: HA
authors.lastname: Santos
authors.forename: Elisabete S
authors.initials: ES
authors.lastname: Ferreira
authors.forename: Elisa J
authors.initials: EJ
authors.lastname: Pereira
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Pereira
authors.forename: Kyösti
authors.initials: K
authors.lastname: Kontturi
authors.forename: Fernando
authors.initials: F
authors.lastname: Silva
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000327:Adsorption; D015374:Biosensing Techniques; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D025802:Electric Capacitance; D004563:Electrochemistry; D004800:Enzymes, Immobilized / Q000737:chemistry; D005025:Ethylene Dichlorides; D005949:Glucose Oxidase / Q000737:chemistry*; D008567:Membranes, Artificial; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D014867:Water
chemical_list: D004800:Enzymes, Immobilized; D005025:Ethylene Dichlorides; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010743:Phospholipids; C097424:dibehenoylphosphatidylcholine; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; C024565:ethylene dichloride; D005949:Glucose Oxidase