Electrostatic immobilization of glucose oxidase in a weak acid, polyelectrolyte hyperbranched ultrathin film on gold: Fabrication, characterization, and enzymatic activity

In this paper we show that hyperbranched polymers can be used as a host matrix for electrostatic entrapment of enzymes, Specifically, amine-functionalized glucose oxidase (GOx(+)) and horseradish peroxidase, as well as poly(amidoamine) dendrimer-modified horseradish peroxidase, reversibly sorb into polyanionic, hyperbranched poly(sodium acrylate) (PAA(-)) films that are on the order of a few hundred angstroms thick. The quantity of GOx(+) entrapped within the PAA(-) films depends on the nature of film preparation but is typically on the order of 0.06 unit/cm(2). The extent to which entrapped GOx(+) retains its activity depends on the film history, but for PAA(-)/GOx(+) composites not exposed to glucose and stored at 4 degrees C, the original activity is retained for up to 68 days and perhaps longer.