A novel mediator-free amperometric sensor based on horseradish peroxidase (HRP)/multi-walled carbon nanotubes (MWCNT)-coated glassy carbon (GC) disk electrode to merge HRP with nano-Au has been developed. The electrochemical behavior of a film of MWCNT on GC was observed and the experiment results demonstrate that the electrode as prepared exhibits direct electron transfer between HRP and GC electrode, and electrocatalytic action toward H₂O₂, which amplify the amperometric response signal, and enhance the sensitivity and stability of the sensor. The biosensor showed a specific response to H₂O₂ in the range 1.0×10^－6 to 1.0×10^－3 mol•L^－1 by CV. Moreover, the reproducibility and stability of the biosensor were also studied.

Key words: multi-walled carbon nanotube, nano-Au, direct electron transfer, horseradish peroxidase