Abstract: The invention provides compositions for stabilizing polynucleic acids and increasing the ability of polynucleic acids to cross cell membranes and act in the interior of a cell. In one aspect, the invention provides a polynucleotide complex between a polynucleotide and certain polyether block copolymers. Preferably, the polynucleotide complex will further include a polycationic polymer. The compositions can further include suitable targeting molecules and surfactants. In another aspect, the invention provides a polynucleotide complex between a polynucleotide and a block copolymer comprising a polyether block and a polycation block. In yet another aspect, the invention provides polynucleotides 10 that have been covalently modified at their 5′ or 3′ end to attach a polyether polymer segment.

Abstract: The present invention is directed to certain block copolymers of alkylethers linked to biologically active agents. More specifically, the invention relates to a conjugate between a biologically active agent and a block copolymer comprising: a biologically active agent covalently linked to a polymer comprising an A-type linear polymeric segment of relatively hydrophilic character, the repeating units of which contribute an average Hansch-Leo fragmental constant of about -0.4 or less and have molecular weight contributions between about 30 and about 500 and a B-type linear polymeric segment of relatively hydrophobic character, the repeating units of which contribute an average Hansch-Leo fragmental constant of about -0.4 or more and have molecular weight contributions between about 30 and about 500, wherein at least about 80% of the linkages joining the repeating units for each said polymeric segment comprise an ether linkage.

Abstract: The invention provides compositions for stabilizing polynucleic acids and increasing the ability of polynucleic acids to cross cell membranes and act in the interior of a cell. In one aspect, the invention provides a polynucleotide complex between a polynucleotide and certain polyether block copolymers. Preferably the polynucleotide complex will further include a polycationic polymer. In another aspect, the invention provides a polynucleotide complex between a polynucleotide and a block copolymer comprising a polyether block and a polycation block. In yet another aspect, the invention provides polynucleotides that have been covalently modified at their 5' or 3' end to attach a polyether polymer segment. In still another aspect, the invention provides certain preferred polycationic polymers.