Discrimination of a copper complex to single- and double-stranded DNA as determined by electrochemical kinetics and thermodynamics

Discrimination of a mix-ligand polypyridyl copper complex, [Cu(phendione)(DAP)]SO4 (phendione = 1,10-phenanthroline-5,6-dione, DAP = 2,3-diaminophenazine) to single-stranded (ss-) and double-stranded (ds-) DNA is presented in this paper. UV absorption spectra suggested that the copper complex could be a typical metallointercalator for dsDNA. Surface-based electrochemical experiments showed that [Cu(phendione)(DAP)]2+ underwent different electrochemical behaviors at ssDNA and dsDNA modified GCE because of the different affinities of the copper complex with ssDNA and dsDNA, which suggested that the copper complex could be an effective discriminator for ssDNA and dsDNA in sensing analysis. The different binding parameters such as binding constant (K) and binding site size (s), and the kinetic and thermodynamic binding parameters of [Cu(phendione)(DAP)]2+ with ssDNA and dsDNA were also evaluated, further quantificationally proving the discrimination ability.