Interaction between immobilized DNA and tris(bpy)osmium(II/III) complex

The interaction between a tris(bipyridyl)osmium (II/III) ion (osmium complex) and immobilized DNA was studied. The amount of immobilized DNA on the prepared carbon paste electrode (surface area; 0.66–2.37×10−2 cm2) was 0.26–2.78×10−4 mol cm−2. Compared with the bare porous electrode (584 mV), the equilibrium potential of osmium complex with the immobilized single strand DNA electrode shifted to the higher side (650 mV). On the other hand, the equilibrium potential of one with the immobilized double strand DNA (dsDNA) electrode shifted to the lower side (542 mV). These results suggest that the osmium complex interacted specifically with dsDNA. The amount of the osmium complex on immobilized dsDNA electrodes was determined and it gave a good linear plot in the concentration range of 0.5 to 4 mM.