Biology Reference
In-Depth Information
ogy era, novel nanostructured composite materials are expected to
bedesignedshowingimprovedpropertiesduetonanostructuration.
The composite materials can also be classified according to the
physical properties in
soft
or
rigidcomposites
.
A
conducting composite
results if at least one of the phases is an
electricalconductor.Theoverallelectricalpropertiesoftheconduct-
ing composite will be determined by the nature, the relative quan-
tities, and the distribution of each phase. Recent developments in
the field of conducting composites applied to electrochemistry have
opened a new range of possibilities for the construction of electro-
chemical sensors and biosensors. The main features of these mate-
rials havebeen described elsewhere indetail [48, 49].
A
polymercomposite
resultsifatleastoneofthecomponentsisa
polymeric matrix, which can be a
conducting
or
nonconducting poly-
mer
. As such, a
conducting polymer composite
can be obtained with
a
conducting polymer
matrix, or, instead, by using
a non-conducting
polymer matrix
but a
conducting filler
(such as platinum, gold, car-
bon,CNT,metal NPs, etc.).
Conducting polymers
are basically organic conjugated poly-
mers, and their unusual electrochemical characteristics (e.g., low
ionization potential, high electrical conductivity, and high electronic
a
nity) are due to the conjugated
π
-electron backbones in their
chemicalcomposition.Thisisthereasonwhytheseconductingpoly-
mers are often called “synthetic metals.” Their organic chains with
single- and double-bonded sp
2
hybridized atoms generate a wide
charge delocalization and therefore are responsible for the metal-
like semiconductive properties of conducting polymers [17]. The
electrical and optical properties of conducting polymers are simi-
lar to those of metals and inorganic semiconductors. Moreover, bio-
molecules can be immobilized onto conducting polymers without
any loss of activity. Their mechanical and electronic properties can
be properly tailored by chemical modeling and synthesis [50]. The
attractive feature of biosensor applications results essentially from
therapidelectrontransferthattheyprovideinelectrodesurfacesas
a consequence of the biological event. Conducting polymers can be
synthesized either by chemical or electrochemical oxidation. Elec-
trochemical method is based on the oxidation of monomers leading
to the formation of cation radicals that repeatedly bind to the grow-
