Patent ID: 6911540

Claim:
A mixed sequence oligonucleotide having the formula: or a salt thereof, wherein: each B independently is a protected or unprotected purine or pyrimidine base in the β-anomeric configuration; W 3 and W 4 are each independently H, PO 3 −2 , a protecting group, or an intermediate moiety in the formation of an internucleotide link which when reacted with the appropriate —OH results in Z; n is an integer of 1-200; each Z is independently P(O)O, P(O)S or P(O)N(R) 2 ; each R is independently H or alkyl (C 1-6 ); each A is H,OH, O—Pr wherein Pr is a protecting group, or X-Y wherein X-Y is O-(unsubstituted alkyl (C 2-20 )), S-(unsubstituted alkyl (C 1-20 )), or NH-(unsubstituted alkyl (C 1-20 )); and at least one A is X-Y.