▎ 摘　　要

A disposable amperometric biosensor was developed for the detection of total polyphenolic compounds from tea infusions. The biosensor was designed by modifying the surface of a carbon screen-printed electrode with platinum nanoparticles and reduced graphene oxide, followed by the laccase drop-casting and stabilization in neutralised 1% Nafion solution. The obtained biosensor was investigated by scanning electron microscopy and electrochemical techniques. It was observed that platinum nanoparticles-reduced graphene oxide composite had synergistic effects on the electron transfer and increased the electroactive surface area of the carbon screen-printed electrode. The constructed analytical tool showed a good linearity in the range 0.2-2 mu M for caffeic acid and a limit of detection of 0.091 mu M. The value of Michaelis-Menten apparent constant was calculated from the electrochemical version of Lineweaver-Burk equation to be 2.75 mu M. This disposable laccase biosensor could be a valuable tool for the estimation of total polyphenolic content from tea infusions. (C) 2013 Elsevier B.V. All rights reserved.