Supramolecular Immobilization of Xanthine Oxidase on Electropolymerized Matrix of Functionalized Hybrid Gold Nanoparticles/Single-Walled Carbon Nanotubes for the Preparation of Electrochemical Biosensors

Glassy carbon electrodes modified with single-walled carbon nanotubes and a three-dimensional network of electropolymerized Au nanoparticles capped with 2-mercaptoethanesulfonic acid, p-aminothiophenol, and 1-adamantanethiol were used as hybrid electrochemical platforms for supramolecular immobilization of a synthesized artificial neoglycoenzyme of xanthine oxidase and beta-cyclodextrin through host-guest interactions. The ensemble was further employed for the bioelectrochemical determination of xanthine. The biosensor showed fast amperometric response within 5 s and a linear behavior in the 50 nM to 9.5 mu M xanthine concentration range with high sensitivity, 2.47 A/(M cm(2)), and very low, detection limit of 40 nM. The stability of the biosensor was significantly improved and the interferences caused by ascorbic and uric acids were noticeably minimized by coating the electrode surface with a Nafion thin film.