Biology Reference
In-Depth Information
transfer, enhanced DNA immobilization, and better stability and
sensitivityofresulting DNA biosensors.
The aim of this review is to describe the possibilities of modern
utilization of conducting as well as nonconducting polymers in the
preparation and application of electrochemical DNA biosensors and
to report their advantages and disadvantages. This chapter deals
mostly with thestate ofthe art inthe last few years.
10.2 Modification of Electrode Surface with Polymers
Polymeric films can be prepared at the surface of metal, glassy
carbon, as well as carbon paste electrodes. The preparation of
conducting polymers at the surface of carbon electrodes employed
in biosensors is already reviewed [1]. The methods mostly used are
solventcasting, spin coating, andelectropolymerization.
10.2.1
Solvent Casting
In solvent casting method an already prepared polymer is first
dissolved in the appropriate solvent and then simply cast onto the
surface of the electrode. After solvent evaporation, the film of poly-
mer is formed. It is a very simple approach, but unfortunately two
disadvantages have to be considered, uniformity of the polymeric
filmandreproducibilityofitspreparation[2].Thismethodisusually
usedforthepreparation ofredox activeornonconductingpolymers
[3].Coatingsofcompositesofnanomaterialswithpolymersarealso
often prepared by this method [4].
10.2.2
Spin Coating
Problem with uniformity and reproducibility can be avoided using
the
spin coating
method. In this case, dissolved polymer is put onto
the electrode surface, which is then rotated at high speed. The
centrifugal force causes the spread of the solution, leading to a
more uniform coating than in the case of solvent casting. During
the rotation, the solvent is evaporated. Problem was reported with
control of the structure and thickness of polymer coatings [5].
