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

Herein, the consecutive incorporation of AgI ion into the dsDNA containing adjacent C-C mispairs is demonstrated. The melting temperature (Tm ) was 8 ° C higher for DNA containing three C-C mispairs upon the addition of three AgI ions as compared to the AgI -free DNA, and no Tm was obtained in the presence of excess AgI ion, indicating a stable bridging of C-AgI -C upon the incorporation of the stoichiometric amount of AgI per C-C mispair. The circular dichroism (CD) spectra of the dsDNA showed a negative peak at ∼270 nm in the presence of excess AgI , implying that significant structural changes and a potential aggregation of DNA occurred. Subsequently, the AgI -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 AgI , respectively. These results are further supported by the XPS and sulfide-Au reductive desorption measurements.