Oligonucleotides are hydrophilic and often have difficulty permeating cell membranes. Cholesterol is hydrophobic, and when conjugated to oligonucleotides, can facilitate uptake into cells. It has been used as a transfection aid for antisense oligos and siRNAs, both in vitro and in vivo. The TEG (15 atom triethylene glycol) spacer further increases cellular uptake.
Cholesterol-TEG is available from IDT for both DNA and RNA oligos on scales from 100 nmole to 10 μmole. Because cholesterol is difficult to manufacture, it requires HPLC purification. To order, select Cholesterol-TEG from the modifications tab on the oligo order page.