Ferrocene-DNA Conjugates

A number of Fc-DNA conjugates were reported in the literature, and a selected number of the reports are summarized in Table 1. Fc-labeled DNA constructs have emerged as an effective tool to investigate DNA hybridization and offer a convenient method for DNA mismatch detection by differential hybridization. 

As mentioned above, the redox label can be introduced as a substituent on a nonnatural nucleoside and then incorporated using solid state synthetic procedures. 

The Fc group provides a convenient method for determining the surface concentration of the adsorbate on the gold surface (3.0X10 mol/cm ). The resulting footprint per molecule is given as 9.8 A, which is larger than for Fc-alkylthiols on 

The target DNA strand can then be hybridized to the sinface-supported strand. This is followed by the hybridization of a Fc-oligonucleotide to a complementary sequence on the ss-DNA target strand. The hybridization event forming the ternary complex wiU result in a detectable electrochemical signal (Fig. 3). 

A significant anodic peak due to oxidation of the Fc moiety was observed for the electrode treated with the target DNA. The peak potential Ef) of 645 mV (vs. Ag/AgCl) for the monolayer was exceedingly positive compared with the redox potential of 430 mV in bulk solution. Importantly, the monolayer is stable even to heating to 80°C without loss of the electrochemical signal. The electrochemical results compare well to those of Letsinger and Mirkin, who also observed a shift to 

---