▎ 摘　　要

A novel water-soluble graphene derivative was prepared from graphene oxide via a two-step modification approach. Graphene oxide was first functionalised with reactive epoxy groups by covalent modification with (3-glycidyloxypropyl) trimethoxysilane and further cross-linked with glycol chitosan. This graphene derivative was characterized using different microscopy and physicochemical methods and employed as a coating material for a glassy carbon electrode. The nanostructured surface was used as a support for the covalent immobilization of the enzyme laccase through cross-linking with glutaraldehyde. The enzyme electrode was tested for the amperometric detection of different phenolic compounds, which displayed excellent analytical behaviour toward catechol with a linear range of response from 200 nM to 15 mu M, sensitivity of 93 mA M-1 cm(-2), and low detection limit of 76 nM. The enzyme biosensor showed high stability when stored at 4 degrees C under dry conditions and was successfully employed to quantify the total phenolic compounds in commercial herbal tea samples.