Consecutive Silver(I) Ion Incorporation into Oligonucleotides containing Cytosine-Cytosine Mispairs.

Herein, the consecutive incorporation of Ag ion into the dsDNA containing adjacent C-C mispairs is demonstrated. The melting temperature (T ) was 8  C higher for DNA containing three C-C mispairs upon the addition of three Ag ions as compared to the Ag -free DNA, and no T was obtained in the presence of excess Ag ion, indicating a stable bridging of C-Ag -C upon the incorporation of the stoichiometric amount of Ag per C-C mispair. The circular dichroism (CD) spectra of the dsDNA showed a negative peak at ∼270 nm in the presence of excess Ag , implying that significant structural changes and a potential aggregation of DNA occurred. Subsequently, the Ag -mediated DNA strands are immobilized on Au surfaces. Their electrochemical properties are monitored using CV, EIS and SECM showing increased overpotentials and charge-transfer resistances, and decreased the rate constant in the presence of an excess of Ag , respectively. These results are further supported by the XPS and sulfide-Au reductive desorption measurements.