3. Electrochemical biosensors
As discussed earlier, the geometry of carbon nanomaterials, 2-D
(planar) in case of graphene and 1-D (tubular) for CNTs, makes
them ideal transduction materials. Additionally, their electrochemical
properties such as faster electron transfer kinetics, low residual
current, readily renewable surface, wide potential window and
enhanced currents with significant reduction in over-potential
make carbon nanomaterials promising candidates for biosensing
applications in comparison to other carbon-based electrode materials
like glassy carbon (Wang et al., 2009). It has been experimentally
demonstrated that the electrochemistry of graphene is driven
by the edge-plane sites that can exhibit an electron transfer rate
(ke) as high as 0.01 cm/s (Pumera et al., 2010). So, the high density
of edge-plane defect sites per unit mass of the material in carbon
nanotubes and chemically modified graphene enhances their electrochemical
activity, making them highly sensitive and selective
transduction materials in comparison to other nanomaterials such
as metal oxide nanowires and conducting polymer films