▎ 摘　　要

Graphene has a unique atom-thick two-dimensional structure and excellent properties, including high conductivity and electron mobility at room temperature, large specific surface area, and excellent mechanical properties. Graphene also possesses a variety of promising electrochemical properties, such as a wide potential window, low charge-transfer resistance, high electrocatalytic activity and fast electron transfer rate. Furthermore, chemically modified graphene materials, particularly graphene oxide (GO) and reduced graphene oxide (rGO), can be produced in a large scale and at low costs. They have good processability and can be assembled, blended or fabricated into macroscopic electrode materials with controlled compositions and microstructures. Thus, graphene and its chemically modified derivatives are unique and attractive electrode materials for electrochemical biosensing. For example, GO is a chemically modified graphene and an important precursor of graphene. GO sheets have a large amount of carboxyl groups at their edges, which can be used to covalently immobilize enzymes, realizing the detection of biomolecules. GO can also enhance the direct charge transfer of protein because of its irreversible adsorption to protein and abundant catalytic sites. However, the oxygen functional groups of GO heavily destroy the conjugated planes of graphene sheets, decreasing the electrical property and limiting the practical applications of GO. Chemical, electrochemical, or thermal reduction can partly restore the conjugated structure, converting GO to conductive rGO. On the other hand, graphene is a material with zero band gap. Doping graphene with heteroatoms can modulate its band gap and improve its electrocatalytic properties. Graphene materials also frequently have to be blended with other functional materials to improve their dispersibility and processibility, enhance their electrochemical activity and/or selectivity. This review will summarize the recent research achievements in electrochemical biosensing based on the electrodes modified with pristine graphene (e.g. GO, rGO, and doped graphene) or graphene composites with biomolecules, polymers, ionic liquids, metal and metal oxide nanoparticles. A perspective of developments in this research field is also provided.