Biology Reference
In-Depth Information
oscillographic polarography without at controlled ac method and
mercuryelectrodes)wassuccessfullyappliedtobiomacromolecules
analysis, especially to DNA and synthetic polynucleotides (reviewed
in [30] and [31]). Later, it was found that AdSV (in connection with
CV and pulse methods [32-34]) represents a sensitive method for
electrochemical analysisof DNA.
Adsorptive transfer stripping voltammetry (AdTSV) was intro-
duced in 1986 as a new analytical procedure based on the
adsorptivepre-concentrationofbiomacromoleculesonanelectrode,
the transfer of the adsorbed layer into a background electrolyte
and subsequent voltammetric analysis [35]. The advantages of
AdTSV were summarized as follows: (i) the method utilizes
differences in adsorbability of substances to their separation, (ii)
due to their strong adsorption, analytes (oligonucleotides) can
be separated from complex media, which are not suitable for
voltammetric analysis of the conventional type, (iii) the interaction
of biomacromolecules immobilized on the surface of the electrode
with substances contained in the solution is possible, and (iv)
all mentioned points can be affected by electrode potential
[35].
Anevenhigherdifferencewasfoundinstirredsolutionwhenthe
anodic peak of guanine was measured instead of the cathodic one
[33]. AdSV measuremets of nucleic acids or oligonucleotides were
also performed by square wave voltammetry and ac voltammetry
[36, 37]. Details about AdSV of nucleic acids were summarized in
several reviews [34, 38-43].
As the first EVLS application to adsorbed electroactive species,
the adsorptive stripping voltammetry of thermally denatured DNA
(ssDNA) on a hanging mercury drop electrode (HMDE) was
performed. While the LSV signal of ssDNA at low concentrations
gives a slight indication of the cathodic peak (due to the reduction
of adenine and cytosine residues), the elimination function (elimi-
nating
I
c
,
I
k
, and conserving
I
d
) provides a clear peak-counterpeak
signal (Fig. 11.1) [7]. Using this EVLS function E4 it is possible to
determine DNA at concentrations below micrograms per milliliter.
In comparison to the SWV (square-wave voltammetric) signal,
the EVLS signal of ssDNA is one and a half times higher. It was
demonstratedthatEVLS,inrelationtotheaccumulationofadsorbed
