Biology Reference
In-Depth Information
DNA adsorption issues is required, a thick DNA layer is more con-
venient. However, the yield in hybridization is better on a thin DNA
layer [36].
Furthermore, GEC has shown unique and selective adsorption
behavior. While DNA is firmly adsorbed under dry conditions, the
wet adsorption of non-specific DNA, proteins, enzymes, or other
biomolecules is negligible under stirring or convection conditions
in solution [25, 79, 80]. The DNA-modified GEC surface does not
require blocking steps to minimize the non-specific adsorption on
the free sites of the surface [36] since the non-specific adsorp-
tion is very low and similar to the instrumental background noise.
Moreover, no blocking reagents are required during hybridization
to reduce the non-specific adsorption. It was previously demon-
strated that the hybridization signals (as well as the non-specific
adsorption signals) were essentially the same when performing the
hybridization without blocking reagents and using different block-
ingcommercialsolution,suchas(i)5XSSC,1XDenhardt's,100
μ
g/ml
chloroform extracted salmon testes DNA, 0.5% (w/v), SDS and 50%
(v/v) formamide; (ii) 5XSSC, 1XDenhardt's, 0.5% (w/v) SDS and
50% (v/v) formamide; and (iii) 5XSSC, 0.5% (w/v) SDS and 50%
(v/v) formamide. Comparable hybridization signals as well as non-
specific adsorption are achieved by using those three different solu-
tionsfor hybridization[25].
3.4.2
Electrochemical Genosensing Based on DNA
Wet Adsorption on GEC as Electrochemical
Transducer
Wet adsorption relies on leaving DNA to interact with the carbona-
ceous surface through physical forces in the presence of water. Dur-
ing wet adsorption, the stabilization of B-DNA is expected to occur
on the carbonaceous surface, by keeping the hydration water of the
DNA molecule. In this case, the hydrated B-DNA form is stabilized
over the GEC surface by weaker forces: as the water is kept on the
DNAadsorbedmolecule,itcanbeeasilydesorbedfromtheGECsur-
face if soaked in aqueous solutions.
DNAcanbeeasilyimmobilizedonGECbysimplewetadsorption
onto GEC surface. A small drop of DNA probe in acetate saline
