Biology Reference
In-Depth Information
Table 12.1. Electroactivity of DNA bases and their detection conditions
Method
Base
Ox/red
Electrode
Peak Potential (V) vs. SCE
pH
DPV
G
Ox
carbon
+1.0
4.8
DPV
G
Ox
carbon
+0.8, +0.9
7.4
−
.
CV
G
Ox for reduced
HMDE
0
3
product
−
.
DPP
A
Red
DME
1
5
Acid/neutral
DPV
A
Ox
carbon
+1.2
4.8
DPP
C
Red
HMDE
−
1
.
5
Acid/neutral
Abbrevations
:DPVisdifferentialpulsevoltammetry;CV,cyclicvoltammetry;andDPP,differential
pulse polarography.
Source
:Ref.6
carbon transducers and C and A at mercury electrode by Trnkova
et al.
[8].
The electrochemical signals of nucleic acid bases were shown to
have insu
cient sensitivity for DNA analysis in the 1960s, because
ofthepoorlydevelopeddetectiondeviceswithoutsoftwaresystems.
However, recent advancements in this field started with digital
potentiostats and sophisticated baseline correction techniques in
connection with differential pulse voltammetry (DPV) [9] and
square wave voltammetry (SWV) [10-12]. Therefore, well-defined
voltammetricpeakshavebeenobtainedfromDNAorRNAatcarbon
electrodes in the last decade [13].
DNA adsorption at carbon electrodes reflected by DPV signals
is sensitive to single/double-stranded DNA structure at electrodes.
When compared with the sensitivity of mercury electrodes, carbon
electrodes are less sensitivefor conformational changes in DNA [6].
12.4 Types of DNA Immobilization Methodologies onto
Sensor Surfaces
Earlier DNA biosensor applications were performed in a solution
phase(DNAsolution)[3,4].However,inthelastdecade,researchers
focused on the ordered structure of DNA onto the sensor surface
because of its high sensitivity for detection of target DNA. For this
reason, scientists prefer synthetic and short DNA fragments with
