The presently disclosed subject matter relates to the delivery of oligonucleotides to cells through the delivery of a composition or reagent comprising a hybridization complex comprising a first antisense oligonucleotide which is modified to have a higher stability against degradation, and a second sense oligonucleotide which is prone to degradation. The presently disclosed subject matter furthermore relates to dendrimeric bioconjugates and compositions or reagents comprising them, wherein the bioconjugate comprises a conjugate moiety coupled to a dendrimeric structure and to their use to deliver oligomeric compounds including oligonucleotides or duplexes, as described above, to cells for modulation of gene expression (i.e. antisense or antigene therapy/research, RNA interference).