Backbone modifications in oligonucleotides and peptide nucleic acid systems.

In the past year major advances have been made in the design, synthesis and characterization of two classes of modified oligonucleotides. In the first class, the phosphodiester backbone of 2'-deoxyribo-oligonucleotides has been replaced in several different ways. The second group represents a completely different type of oligonucleotide modification in which the backbone and the 2'-deoxyribose moieties are replaced by amino acids. These advances present new possibilities for the pharmaceutical applications of modified oligonucleotides in antisense strategies.