Hemoglobin-graphene modified carbon fiber microelectrode for direct electrochemistry and electrochemical H2O2 sensing

ABSTRACT Microelectrodes have received tremendous attention in different fields due to their unique electrochemical properties caused by small size. Here, we report a facile method for fabricating a hemoglobin-graphene modified carbon fiber microelectrode (Hb/GCFME) as a H 2 O 2 electrochemical microsensor. Three-dimensional porous graphene layer was deposited electrochemically on the surface of carbon fiber, and then hemoglobin was introduced by a simple dipping method. The immobilized hemoglobin retains its bioactivity and the direct electrochemistry of hemoglobin at Hb/GCFME exhibits a couple of well-defined redox peaks with a formal potential of −0.36 V. Moreover, Hb/GCFME shows a good electro-catalytic activity towards H 2 O 2 and can be used for sensitive detection of H 2 O 2 . By amperometry, the microbiosensor exhibits a wider linearity range from 8.0 μM to 0.21 mM with a detection limit of 2.0 μM and much higher sensitivity of 1.4 mA cm −2  mM −1 . This microsensor has potential application in the detection of H 2 O 2 in microsystems, and the method developed in this paper offers a new way for fabricating redox protein/enzyme-based microsensors.