A pencil graphite electrode modified by monovalent copper: a promising tool for the biosensing of
                                              purines


Rudolf Navrátil


A pencil graphite electrode (PeGE) is a simple, cheap and non-toxic prototype of electrochemical
sensor. It can have multiple uses, such as determining the oxidation behavior of biologically
active substances that play a key role in the metabolic processes of living organisms [1]. In this
work PeGE is used for the analysis of purine derivatives. For these purposes the adsorptive
stripping technique in combination with linear sweep voltammetry (LSV) and elimination voltammetry
(EVLS) was used. To increase the sensitivity of purine detection our analysis was carried out in
the presence of copper ions Cu (II) which are able, through their reduced form, to generate
slightly soluble complexes with purines [2, 3]. The Cu (I)-purine complexes are adsorptive species
on PeGE surfaces. The formation and stability of these complexes influenced by experimental
conditions (pH, Cu(II) concentration) and the substituents on purine skeleton were investigated. It
was found that even a very small Cu-modification in the surface structure of PeGE significantly
affects oxidative signals of purines. On the basis of comparative experiments PeGE was selected as
potentially the most appropriate electrode for purine sensors.


[1]        G. Dryhurst, Electrochemistry of Biological Molecules, Academic Press, New York, 1977.

[2]       R. Navratil, I. Pilarova, F. Jelen, L. Trnkova, Int. J. Electrochem. Sci., 2013,
8(4), 4397-4408.

[3]       L. Trnkova, F. Jelen, M. Ozsoz, Electrochemical Transducer for Oligonucleotide Biosensor
Based on the Elimination and Adsorptive Transfer Techniques 2012.