Electrochemical detection of nucleic acids using pentaferrocenyl phosphoramidate α-oligonucleotides

We report the synthesis of alpha-oligonucleotides exhibiting five phosphoramidate linkages bearing a ferrocenyl (Fc) moiety. Three different linkers: ethyl, propyl and 4-methyl-1-ethyl-1,2,3-triazol between the ferrocene (Fc) residue and the phosphoramidate function have been studied. We demonstrated that these Fc(5)-alpha-DNA conjugates exhibit similar or even better stability than the wild type beta-DNA when hybridized to their complementary beta-DNA. Their electrochemical behavior studied in solution by cyclic voltammetry showed that this original structure leads to a strong difference in the Fc environment when the probe is alone or hybridized with a complementary strand. These preliminary electrochemical analyses are very encouraging and augur a good sensitivity of these probes for DNA detection after grafting on an electrode microsystem.