Biology Reference
In-Depth Information
epoxy-H77-graphite (20%). The optimal composition in each case
wasobtainedfromthepercolationcurve[52].Asshowninthescan-
ningelectronmicrographs,completelydifferentmaterialshavebeen
obtained with different polymeric binders. Moreover, the polymeric
bindersaccept different “optimal” amount ofgraphite.
Being in the nanotechnology era, novel nanostructured compos-
itematerialsareexpectedtobedesignedshowingimprovedproper-
ties due to nanostructuration. Moreover, composite electrodes from
expensive metals (gold, platinum, etc.) can be prepared using the
NPs as conductive fillers, with enhanced properties but at lower
prices compared to their pure conductor counterparts.
Rigidcarbon-polymercompositeelectrodesoffermanypotential
advantages compared to more traditional electrodes consisting of
a surface-modified continuous conducting material. Rigid carbon-
polymer composite electrodes can often be fabricated with great
flexibility in size and shape, allowing the construction of different
electrodeconfigurations.Rigidcompositesurfacescanbesmoothed
or polished to provide fresh active material ready to be used in a
new assay. Each new surface yields reproducible results because
all individual compounds are homogeneously dispersed in the bulk
of the composite. Moreover, rigid carbon-polymer composites show
improved electrochemical performances, similar to an array of car-
bonfibersseparatedbyaninsulatingmatrixandconnectedinparal-
lel. The signal produced by this macroelectrode formed by a carbon
fiber ensemble is the sum of the signals of the individual microelec-
trodes. Composite electrodes thus showed a higher signal-to-noise
(S/N) ratio than the corresponding pure conductors, accompanied
by an improved electrochemical behavior[46].
3.3.3
Graphite-Epoxy Composites
Rigid conducting graphite-epoxy composites (GEC) [25, 35, 36] and
biocomposites (GEB) [18, 23] have been extensively used in our
laboratories for electrochemical (bio)sensing due to their unique
physical and electrochemical properties. In particular, we have used
GEC (graphite-epoxy composite) made by mixing the nonconduct-
ingepoxyresin(Epo-Tek,EpoxyTechnology,Billerica,MA,USA)with
graphite microparticles (particle sizebelow 50
μ
m).
