RNase H-competent phosphorothioates (S-DNAs) have dominated the antisense field in
large part because they offer reasonable resistance to nucleases, they afford good efficacy
in cell-free test systems, they can be targeted against sites throughout the RNA transcript of
a gene, and they are widely available from commercial sources at modest prices. However,
these merits are counterbalanced by significant limitations, including: degradation by
nucleases, poor in-cell targeting predictability, low sequence specificity, and a variety of non …