Multilayered assembly of dendrimers with enzymes on gold: Thickness-controlled biosensing interface

A new approach to construct a multilayered enzyme film on the Au surface fo r use as a biosensing interface is described, The film was prepared by alte rnate layer-by-layer depositions of G4 poly(amidoamine) dendrimers and peri odate-oxidized glucose oxidase (GOx), The cyclic voltammograms obtained fro m the Au electrodes modified with the GOx/dendrimer multilayers revealed th at bioelectrocatalytic response is directly correlated to the number of dep osited bilayers, that is, to the amount of active enzyme immobilized on the Au electrode surface. From the analysis of voltammetric signals, the cover age of active enzyme per GOx/dendrimer bilayer during the multilayer-formin g steps was estimated, which demonstrates that the multilayer is constructe d in a spatially ordered manner. Also, with the ellipsometric measurements, a linear increment of the film thickness was registered, supporting the fo rmation of the proposed multilayered structure. The E5D5 electrode showed t he sensitivity of 14.7 mu A.mM(-1) glucose.cm(-2) and remained stable over 20 days under day-by-day calibrations. The proposed method is simple and wo uld be applicable to the constructions of thickness- and sensitivity-contro llable biosensing interfaces composed of multienzymes as well as a single e nzyme.