▎ 摘　　要

This article reports a novel electrochemical sensor based on a nanocomposite for the sensitive determination of Thyroxine (T-4), the active form of the hormone. Hydrodynamic amperometry is performed with a nanocomposite electrode based on the dispersion of a graphene-based filler hybrid-nanomaterial throughout an insulating epoxy resin in the optimum composition ratio (the near-percolation composition). This hybrid-nanomaterial consists of reduced graphene oxide tuned with gold nanoparticles and a biorecognition agent, the thiolated beta-cyclodextrin. Recognition of T-4 is accomplished via supramolecular chemistry, due to the formation of an inclusion complex between beta-cyclodextrin and T-4. The amperometric device operates at +0.85 V vs. Ag/AgCl, where the oxidation of T-4 takes place on the electrode surface. The sensor covers the 1.00 nM to 14 nM T(4)concentration range in a 0.1 M HCl solution, with a detection limit of 1.00 +/- A 0.02 nM. The sensor can be easily reset by polishing. It exhibits the lowest detection limit regarding to any other electrochemical electrodes for T-4 determination previously described in literature.