Multilayered construction of glucose oxidase and poly(allylamine)ferrocene on gold electrodes by means of layer-by-layer covalent attachment

Highly stable glucose oxidase multilayer films were fabricated on cystamine modified Au electrode surfaces by layer-by-layer covalent attachment of periodate-oxidized glucose oxidase (GOx) and redox polymer poly(allylamine)ferrocene (PAA-Fc) for use as biosensoring interfaces. The fabrication process was followed by cyclic voltammetry. One well stably reversible redox peak with a small peak separation (ca. 0.045 V at 0.05 V s−1) is observed for the multilayer GOx/PAA-Fc film electrode in 0.1 M acetate buffer solution, and the coverage of redox mediators (PAA-Fc) on the electrode surface increases with the multilayer growth cycles, suggesting a progressive deposition process. The GOx/PAA-Fc multilayered electrode exhibits excellent catalytic activities for the oxidation of glucose in 0.1 M acetate buffer solution, and the catalytic current was linearly dependent on the number of assembled layers. This means that control of the number of GOx/PAA-Fc bilayers associated with the Au electrode allows tuning of the sensor sensitivity. The eight bilayers of GOx/PAA-Fc assembly showed the sensitivity of 17.7 μA mM−1 glucose cm−2, and remained stable over 40 days under periodic calibrations.