Biology Reference
In-Depth Information
Figure 3.4.
Different detection strategies in electrochemical genosensing
based on GEC transducers. See also Color Insert.
of GEC composed of islands of conducting material within the non-
conducting and hydrophobic epoxy resin could play an important
role in stabilizing the dehydrated A-form of DNA adsorbed on GEC.
Once immobilized on GEC, DNA preserves its unique hybridization
properties, which can be revealed using different strategies based
on both enzymatic labeling and the intrinsic signal coming from the
DNA oxidation, as schematically shown in Fig. 3.4.
The DNA immobilization on GEC surface by dry adsorption was
performed by covering the GEC surface with a small drop of DNA
in 10 X SSC, and allowing the electrode to dry at 80
◦
C for 45 min
in upright position [25]. The DNA electrochemical detection was
then achieved by an enzymatic labeling step [36]. Briefly, the pro-
cedure consists of the following steps: (i) DNA target immobiliza-
tion; (ii) hybridization with the complementary probe modified
with either biotin or digoxigenin; (iii) enzyme labeling of the DNA
duplex using streptavidin-HRP or anti-DIG-HRP; and (iv) ampero-
metric determination based on the enzyme activity by adding H
2
O
2
