“…[5][6][7][8] Numerous efforts have been made to increase the cellular uptake of antisense oligonucleotides by covalently attaching various chemical groups. Examples are conjugates with cationic compounds, such as poly-(L)-lysine 9 or polyamides, 10 lipophilic conjugates, such as cholesterol, 11 long chain alcohols, 12 phospholipids, 13 aromatic compounds, 14 as well as polyethylene glycol. 15 Furthermore, the effect of attachment of these compounds at different position of the oligonucleotides including the bases, the backbone and the 3 ' -or 5 ' end was investigated.…”