polymers can also be natural polysaccharides containing amino acids or carboxylic acids e g galacturonic acid glucuronic acid mannuronic acid hyaluronic acid pectic acid neuraminic acid alginic acid carrageenan aminated polysaccharides or oligosaccharides linear or branched or carboxylated polysaccharides or oligosaccharides e g reacted with derivatives of carbonic acids with resultant linking of carboxylic groups preferably the opsonization inhibiting moiety is a peg ppg or derivatives thereof liposomes modified with peg or peg derivatives are sometimes called u201c pegylated liposomes u201d the opsonization inhibiting moiety can be bound to the liposome membrane by any one of numerous well known techniques for example an n hydroxysuccinimide ester of peg can be bound to a phosphatidyl ethanolamine lipid soluble anchor and then bound to a membrane similarly a dextran polymer can be derivatized with a stearylamine lipid soluble anchor via reductive amination using na cn bh 3 and a solvent mixture such as tetrahydrofuran and water in a 30 12 ratio at 60 u00b0 c recombinant plasmids which express sirna of the invention are discussed above such recombinant plasmids can also be administered directly or in conjunction with a suitable delivery reagent including the mirus transit lt1 lipophilic reagent lipofectin lipofectamine cellfectin polycations e g polylysine or liposomes recombinant viral vectors which express sirna of the invention are also discussed above and methods for delivering such vectors to an area of.