Layer-by-layer self-assembly of glucose oxidase and Os(Bpy)2CIPyCH2NH-poly(allylamine) bioelectrode

The uptake of glucose oxidase (GOx) onto a polycationic redox polymer (PAA-Os)-modified surface, by adsorption from dilute aqueous GOx solutions, was followed by the quartz crystal microbalance (QCM) and shows double exponential kinetics. The electrochemistry of the layer-by-layer-deposited redox-active polymer was followed by cyclic voltammetry in glucose-free solutions, and the enzyme catalysis mediated by the redox polymer was studied in beta-D-glucose-containing solutions. AFM studies of the different layers showed the existence of large two dimension enzyme aggregates on the osmium polymer for 1 microM GOx and less aggregation for 50 nM GOx solutions. When the short alkanethiol, 2,2'-diaminoethyldisulfide was preadsorbed onto gold, a monoexponential adsorption law was observed, and single GOx enzyme molecules could be seen on the surface where the enzyme was adsorbed from 50 nM GOx in water.