Biology Reference
In-Depth Information
adsorption of the label and a sensitive detection of the hybridiza-
tionevent.Graphite-epoxycomposites(GEC)fulfillalltheserequire-
ments.
In the present work, graphite-epoxy composite, biocomposite,
and nanocomposite materials for the development of electrochem-
ical genosensors are reviewed. Different graphite-epoxy platforms
for electrochemical genosensing, as well as strategies for detect-
ing DNA hybridization are presented. The advantages of these new
graphite-epoxy platforms for electrochemical genosensing are dis-
cussed and compared with the current state of the art in DNA sens-
ing techniques.
3.4 Electrochemical Genosensing Based on
Graphite-Epoxy Composite
3.4.1
Electrochemical Genosensing Based on DNA
Dry Adsorption on GEC as Electrochemical
Transducer
Adsorption is an easy way to attach nucleic acids to solid surfaces,
sincenoreagentsormodified-DNAarerequired,asshowninFig.3.3.
Thesefeatureshavepromotedextensiveuseofadsorptionasimmo-
bilization methodology in genetic analysis. The mainly claimed dis-
advantages of adsorption with respect to covalent immobilization
are(i)nucleicacidsmaybereadilydesorbedfromthesubstrateand
(ii) base moieties may be unavailable for hybridization if they are
bonded to the substrate in multiple sites [76]. However, the electro-
chemical detection strategy based on the intrinsic oxidation of DNA
requires the DNA to be adsorbed in close contact with the electro-
chemical substrateby multisiteattachment, asschematically shown
in Fig. 3.4. This multisite attachment of DNA can be thus detrimen-
tal for its hybridization but is crucial for the detection based on its
oxidation signals. The common method for the multisite physical
adsorption of DNA on carbonaceous-based materials can be classi-
fied into dry or wetadsorptions.
Dryadsorption
reliesonleavingDNAtodryonthecarbonaceous
surface. It can be assisted by light treatment (except UV that is able
