Multilayered construction of glucose oxidase and gold nanoparticles on Au electrodes based on layer-by-layer covalent attachment

A feasible approach to construct multilayer films of glucose oxidase/gold nanoparticles on the Au electrode surface using a cysteamine as a covalent attachment cross-linker is described. The layer-by-layer covalent attachment process was followed and confirmed by electrochemical impedance spectroscopy. On the basis of the studies of UV–Vis spectroscopy and cyclic voltammetry, we demonstrated that the GOD/GNPs multilayer film was formed in a progressive and uniform manner. The CV experiments revealed that the Au electrodes modified with the GOD/GNPs multilayers exhibited an excellent bioelectrocatalytic response to the oxidation of glucose and that the bioelectrocatalytic response was directly correlated to the number of deposited bilayers, that is, to the amount of active enzyme immobilized on the Au electrode surface. The biosensor constructed with six bilayers of GOD/GNPs showed a wide linear response to glucose in the range of 1.0 × 10−5–1.3 × 10−2 M, with a fast response less than 4 s, high sensitivity of 5.72 μA mM−1 cm−2, as well as good stability and long-term life. The proposed method would be applied to the constructions of thickness and sensitivity controllable biosensing interfaces composed of multienzymes as well as a single enzyme.