This invention provides a method for the in vivo delivery of oligonucleotides. The invention utilizes the presence of one or plurality of HES linked to an oligonucleotide to deliver a nucleic acid sequence of interest into the cytoplasm of cells and tissues of live organisms. The delivery vehicle is nontoxic to cells and organisms. Since delivery is sequence-independent and crosses membranes in a receptor-independent manner, the delivered oligonucleotide can target complementary sequences in the cytoplasm as well as in the nucleus of live cells. Sequences of bacterial or viral origin can also be targeted. The method can be used for delivery of genes coding for expression of specific proteins, antisense oligonucleotides, siRNAs, shRNAs, Dicer substrates, miRNAs, anti-miRNAs or any nucleic acid sequence in a living organism. The latter include mammals, plants, and microorganisms such as bacteria, protozoa, and viruses.
