Voltammetry of microparticles, scanning electrochemical microscopy and scanning tunneling microscopy applied to the study of dsDNA binding and damage by scorpiand-like polyamine receptors

Microparticulate deposits of scorpiand-like azamacrocyclic receptors (L1–L4) attached to graphite electrodes provide distinctive voltammetric features in contact with aqueous DNA solutions at biological pH, denoting the formation of DNA surface complexes. This voltammetry allows for screening dsDNA, ssDNA and G-Quadruplex DNA using L4-modified electrodes. Scanning electrochemical microscopy and scanning tunneling microscopy examination of dsDNA fibers attached to the substrate electrode in contact with DMSO solutions containing ferrocene and receptor indicate that a synergic effect is exerted between electrochemically generated ferrocenium ion and the receptors so that they increase mutually their binding ability to dsDNA. Experiments in air-saturated DMSO suggest that there are specific binding sites in dsDNA able to react with electrochemically generated superoxide ion and that such binding sites can be blocked by coordinating receptors.