Biology Reference
In-Depth Information
biotin-modified DNA probe was immobilized in order to prepare a
DNA hybridization biosensor [39]. Direct DNA immobilization via
EDC-NHScouplingwascomparedtoindirecta
nityimmobilization
onto the Ppy-PVS modified Pt electrode [40]. It was found that
covalentDNAimmobilizationshowedfasterredoxprocessesandled
toenhancedsensitivity,whichwasascribedtoincreasedinteraction
of ODNsstationed nearthe Ppy-PVS surface.
10.3.2
Immobilization of DNA Within a Polymeric Matrix
by Electropolymerization
Another widely used method of the DNA immobilization is incorpo-
rationofDNAintothepolymermatrixduringelectropolymerization.
As it was described previously, negatively charged biomolecules,
such as DNA and oligonucleotides, can be advantageously employed
as dopants of a positively charged polymeric structure. The control
of the current density in the galvanostatic method or potential in
thepotentiostaticmethodduringtheelectropolymerizationprocess
is very important to avoid loss of bioactivity or decomposition
of entrapped biomolecules. This method is widely used in the
case of conducting polymers, such as Ppy and PANI. Biomolecule
immobilization is realized in the solution containing monomer and
biomolecules. In this case DNA acts as solo dopant [41, 42]. In this
process, the supporting electrolyte (NaCl, LiClO
4
) can be used to
permitthegrowthofthefilmwithlowconcentrationofsampleODN
[43].
10.4 Application of Synthetic Polymers in DNA
Biosensors
10.4.1
Electronically (Intrinsically) Conducting Polymers
Conducting polymers (CPs) are very popular matrices suitable
for biomolecule immobilization in biosensors [44]. They show a
suitable flexibility and can be chemically modified as required. The
advantage of CPs is that their electrochemical synthesis allows
direct deposition of a polymer on the electrode surface while
