Synthesis and characterization of ferrocene-labeled oligodeoxynucleotides

Using a facile on-column derivatization procedure, oligodeoxynucleotides (ODNs) are labeled with a ferrocene derivative at specific sites. A Sonagashira cross-coupling reaction, using Pd(PPh3)4 and CuI, links ferrocene propargylamide to a halogenated base, such as 2′-deoxy-5-iodouridine or 8-bromo-2′-deoxyadenosine, which has been previously incorporated in the ODN strand. The structure and stability of the DNA duplex are not significantly altered after site-specific labeling with ferrocene, as demonstrated by Tm and CD spectroscopy.