Biology Reference
In-Depth Information
Figure9.2.
Somecommerciallyavailablescreen-printedelectrodesshow-
ing different electrode configurations. See also ColorInsert.
Carbon and gold have a wide use in the technology of disposable
sensors as electrodic materials [8]. Gold has been employed as
electrodic material for the genosensors construction for years, and
carbon is especially used due to its great superficial chemistry,
its low background current, the wide potential window at which
it is possible to be employed, its low cost, and its chemical
passivity. Nevertheless, the electronic-transfer rate obtained with
carbon-based electrodes is lower than that obtained with metallic
electrodes [9].
However, this disadvantage can be overcome by means of the
surface modification of these electrodes with nanostructures, as the
use of carbon nanotubes (CNTs) [10], or gold nanoparticles [11],
since they improve the electronic transfer of the surface of the
electrode, and improve the analytical characteristics offered by the
sensor. Carbon nanofibers can also be used to modify the electrodic
surface in order to improve the analytical characteristics of the
transducer.
In addition, SPEs surfaces have also been covered with a wide
variety of substances: bismuth oxide, Prussian Blue, ferrocyanide,
Meldola's Blue, Co-phthalocyanine, or some enzymes, in order to
obtain suitabletransducers for specific analytes.
9.3 Genosensors on Screen-Printed Electrodes
DNA detection is usually performed by hybridization. For designing
a genosensor, the crucial steps are the choice of the transducer
surface and the immobilization of the single-stranded (ssDNA)
