Electrochemical characterization and analytical application of arsenopyrite
mineral in non-aqueous solutions by voltammetry and potentiometry
Since the electrochemical oxidation peaks of both DNA and anti-tumor drug tamoxifen (TAM) overlapped
with each other, the known electrochemical methods were limited in the study of the interactions
between DNA and TAM. In this paper, zero current potentiometry, a new electrochemical method, was
used to study the interaction of calf thymus dsDNA with TAM. The dsDNA was immobilized on the
surface of carbon paste (dsDNA/CP). The dsDNA/CP connected in series between the clips of working
and counter electrodes of a potentiostat and a reference electrode were immersed in aqueous solution
containing TAM, the interaction of dsDNA with TAM produced a change in interfacial potential at the
dsDNA/CP/solution interface. When linear sweep potential was applied to the dsDNA/CP and the corresponding
I–E curve was recorded, interfacial potential offset applied potential partially, making the I–E
curve displace along potential axis. Zero current potential where circuit current I was equal to zero in the
I–E curve was measured to check the displacement of the I–E curve. Based on the displacement, the thermodynamic
constants of the interaction between dsDNA and TAM were determined. The binding ratio of
dsDNA with TAM was found to be 1:1 and the apparent binding constant was (6.85 ± 0.20) × 106 M−1. As
zero current potentiometry was independent of the changes in redox potential or current of both dsDNA
and TAM themselves, the interaction was studied in their natural forms without damage. Moreover, TAM
can be determined. The detection limit was 1.1 × 10−7 M.