A new sensor design is reported for the construction of an amperometric enzyme biosensor toward H (2)O(2). It was based in the supramolecular immobilization of alternating layers of horseradish peroxidase (either modified with 1-adamantane or beta-cyclodextrin-branched carboxymethylcellulose residues) on Au electrodes coated with polythiolated beta-cyclodextrin polymer. The analytical response of the electrodes, using 1 mM hydroquinone as an electrochemical mediator, increases when the number of enzyme layers increases. The biosensor having three enzyme layers showed a sensitivity of 720 microA/M cm (2) and a detection limit of 2 microM and retained 96% of its initial activity after 30 days of storage. The host-guest supramolecular nature of the immobilization method was confirmed by cyclic voltammetry.

Horseradish peroxidase, previously modified with 1-adamantane moieties, was supramolecularly immobilized on gold electrodes coated with perthiolated b-cyclodextrin. The functionalized electrode was employed for the construction of an amperometric biosensor device for hydrogen peroxide using 1 mM hydroquinone as electrochemical mediator. The biosensor exhibited a fast amperometric response (6 s) and a good linear response toward H 2 O 2 concentration between 12 mM and 450 mM. The biosensor showed a sensitivity of 1.02 mA/M cm 2 , and a very low detection limit of 5 mM. The electrode retained 97% of its initial electrocatalytic activity after 30 days of storage at 4 0 C in 50 mM sodium phosphate buffer, pH 7.0.

Xanthine oxidase modified with 1-adamantanyl residues was supramolecularly immobilized on Au electrodes coated with Au nanoparticles coated with a perthiolated beta-cyclodextrin polymer; the analytical response of the electrode toward xanthine was evaluated.

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