Patent ID: 7943762

Claim:
An oligomer comprising a sequence of morpholino subunits, each morpholino subunit comprising a base-pairing moiety, such that the oligomer can bind in a sequence-specific manner to a target nucleic acid, wherein the morpholino subunits are each joined by a phosphorus-containing intersubunit linkage having the structure: wherein: W is S or O; X is NR 1 R 2 or OR 6 ; Y is O or NR 7 ; and the intersubunit linkage is, at each occurrence, independently: linkage (a), where each of R 1 , R 2 , R 6 and R 7 is independently hydrogen or lower alkyl; or linkage (b1), where X is NR 1 R 2 , Y is O and NR 1 R 2 is a piperazino group, such that R 1 R 2 is —CHRCHRN(R 3 )(R 4 )CHRCHR—, wherein: each R is, at each occurrence, independently H or CH 3 ; R 4 is H, CH 3 or an electron pair; and R 3 is H, lower alkyl, —C(═NH)NH 2 , —Z-L-NHC(═NH)NH 2 or —[C(O)CHR′NH] m H, where Z is carbonyl (C(O)) or a direct bond, L is an optional linker up to 18 atoms in length comprising alkyl, alkoxy or alkylamino groups, or combinations thereof, R′ is a side chain of a naturally occurring amino acid or a one- or two-carbon homolog thereof, and m is 1 to 6; and at least one intersubunit linkage is linkage (b1).