Lipophilic groups, such as cholesteryl, may enhance the permeation of cell membranes for optimal activity. This is particularly intersting for antisense oligonucleotides which must cross the cell membrane for optimal activity.
dR-Cholesteryl (deoxyribose-Cholesteryl) modification allows the synthesis of oligonucleotides containing successive molecules of Cholesteryl anywhere in the sequence or on either terminus. Each label is linked to the deoxyribose via a 6 carbon atoms spacer. Each dR-Cholesteryl can also be separated by a spacer.