Biomedical Engineering Reference
In-Depth Information
Figure 12.24
FE-SEM images of the imprinted (a,b) and control (c,d) electrospun
nanoi bermats with the dif erent concentration of monomers used during their synthesis
(Reproduced with permission from [54]).
arranged in a tetrahedron, graphite is formed as a 2D sheet of carbon
atoms arranged in a hexagonal array. In this case, each carbon atom has
three nearest neighbors. “Rolling” sheets of graphite into cylinders forms
carbon nanotubes. h e properties of nanotubes depend on atomic arrange-
ment (how the sheets of graphite are “rolled”), the diameter and length
of the tubes, and the morphology, or nanostructure [55].
h e two main
types of CNTs are single-walled CNTs (SWCNTs) and multiwalled car-
bon nanotubes (MWCNTs). Single-walled CNTs are sp
2
-hybridized car-
bon in a hexagonal honeycomb structure that is rolled into hollow tube
morphology. Multiwalled CNTs are multiple concentric tubes encircling
one another [56]. h e SWCNTs can be classii ed as either semiconducting
or metallic allotropes, depending on the chirality. h e distinction of semi-
conducting or metallic is important for their use in dif erent sensors but
the physical separation of allotropes has proven to be one of the more dif-
i cult challenges to overcome. In MWCNTs, a single metallic layer results
in the entire nanotube displaying metallic behavior. Due to a cheaper and
easier synthesis procedure, MWCNTs are more widely used as compared
to SWCNTs.
h e MWCNTs were employed as medium for electron transfer and the
electrocatalyst to enhance the sensitivity of the electrochemical detection
in electrochemical sensor. h e poor solubility of carbon nanotubes in
