Antisense oligonucleotides promise to be highly potent therapeutic agents. Nanomolar extracellular concns. of phosphorothioate oligonucleotides have been reported to significantly alter gene expression in cultured cells. (Tidd, 1990). PEG derived hydrogels appear to be appropriate for delivering these concns. or higher for prolonged periods of time, and should protect the antisense oligonucleotides from enzymic degrdn. prior to cellular uptake. Release from these hydrogels follows predictable and alterable kinetics. The addnl. ability to polymerize the oligonucleotide-contg. macromer soln. in situ makes this advancement particularly exciting. [on SciFinder (R)]