LAYER-BY-LAYER SELF-ASSEMBLY OF GLUCOSE-OXIDASE WITH A POLY(ALLYLAMINE)FERROCENE REDOX MEDIATOR

We report the redox mediation of glucose oxidase (GOx) in a self-assem bled structure of cationic poly(allylamine) modified by ferrocene (PAA -Fc) and anionic GOx deposited electrostatically layer-by-layer on neg atively charged alkanethiol-modified Au surfaces. Successive PAA-Fc an d GOx layers were deposited by alternate immersion of the thiol-modifi ed Au in the respective polyelectrolyte and enzyme solutions. The upta ke of thiol, redox polymer, and GOx on the surface was monitored by qu artz crystal microbalance. Cyclic voltammetry shows nearly ideal surfa ce waves of ferrocene in the polymer with charge independent of sweep rate; the redox surface concentration was obtained from integration of the ferrocene/ferricinium voltammetric peaks. The redox charge increa ses in step with the number of PAA-Be layers deposited. Enzyme catalys is for the oxidation of beta-D-glucose was achieved with a multilayer PAA-Fc/GOx assembly, with each GOx layer contributing equally to the c atalytic response. Only a small fraction of the active assembled GOx m olecules are ''electrically wired'' by the ferrocene polymer although all of the enzyme could be oxidized by soluble ferrocenesulfonate when added to solution.