2'-Fluoro-deoxyadenosine (2'-F-A, Figure 1) confers thermodynamical stability to an oligonucleotide during hybridization of the oligo with its target. When incorporated into an antisense, the duplex Tm increases by 1.8 °C per 2'-F residue added, compared to the native antisense. In RNA oligos, it is suggestable to additionally phosphorothiolate the 2'-F RNA phosphodiester linkages, to increase the oligo resistance to RNase H.
Figure 1. Structure of 2’-F-A (R = sequence).
metabion offers 2’-F-A in its standard portfolio: