Biology Reference
In-Depth Information
Electropolymerized polymers are molecular composites containing
cationic polymer backbone counter anions for maintenance of
charge neutrality [12]. Anions from the electrolyte solution or other
negatively charged molecules present in the electrolyte solution
during electropolymerization can be employed as dopants. For
example, the polypyrrole/ferrocyanide-film-modified carbon paste
electrode was prepared by potentiostatic electropolymerization of
pyrrole in the presence of ferrocyanide ions [13]. Incorporated
ferrocyanide worked as amediator ofascorbic acid oxidation.
10.3 Polymer-Assisted DNA Immobilization
Polymer-assisted immobilization of biomolecules, including DNA, is
widelyreviewed[14-18].DNAcanbeeitherimmobilizedatthesur-
face of polymer-modified electrode or incorporated in the polymer
layer. In the second case, the method of electropolymerization is
mostly used.
10.3.1
Immobilization of DNA onto Polymer-Modified
Electrode Surface
DNA can be attached to the polymer-modified electrode surface
using several methods: simple adsorption, covalent bonds (first
appropriate functional groups are introduced to the polymer, then
DNA iscovalently attached), or a
nity binding(avidin-biotin).
Adsorption
is the simplest method of DNA immobilization, and
it can be achieved by different ways. A polymer-modified electrode
canbesimplydippedintothesolutioncontainingDNA[19]oradrop
ofDNAsolutioniscastontothepolymer-modifiedelectrode surface
and let to evaporate to dry [20]. It is also convenient to use negative
charge of DNA for its adsorption onto positively charged polymer
via electrostatic forces [21]. Electrostatic adsorption of DNA onto
conducting Ppy is well studied [22]. It was found that this process
issignificantlypHdependentandishigherinacidicmediaaswellas
at high ionic strength. Dielectric studies showed that DNA formed
an insulating layer at the surface, which significantly diminished
the ionic conductivity character and maintained the mobility of the
