Layer-by-Layer Self-Assembly of Glucose Oxidase with a Poly(allylamine)ferrocene Redox Mediator

JOSE HODAK; ROBERTO ETCHENIQUE; ERNESTO J. CALVO; KAVITA SINGHAL; PHILIP N. BARTLETT

LANGMUIR

Año: 1997 vol. 12 p. 2708 - 2716

0743-7463

We report the redox mediation of glucose oxidase (GOx) in a self-assembled structure of cationic poly-(allylamine) modified by ferrocene (PAA-Fc) and anionic GOx deposited electrostatically layer-by-layer onnegatively charged alkanethiol-modified Au surfaces. Successive PAA-Fc and GOx layers were depositedby alternate immersion of the thiol-modified Au in the respective polyelectrolyte and enzyme solutions.The uptake of thiol, redox polymer, and GOx on the surface was monitored by quartz crystal microbalance.Cyclic voltammetry shows nearly ideal surface waves of ferrocene in the polymer with charge independentof sweep rate; the redox surface concentration was obtained from integration of the ferrocene/ferriciniumvoltammetric peaks. The redox charge increases in step with the number of PAA-Fc layers deposited.Enzyme catalysis for the oxidation of â-D-glucose was achieved with a multilayer PAA-Fc/GOx assembly,with each GOx layer contributing equally to the catalytic response. Only a small fraction of the activeassembled GOx molecules are “electrically wired” by the ferrocene polymer although all of the enzymecould be oxidized by soluble ferrocenesulfonate when added to solution.