Can a phosphorothioated oligo for antisense studies be used in medium containing serum, and what will be its half life?
Antisense oligos containing phosphorothioate bonds can be used in medium containing serum. However, it is recommended that you inactivate the exonucleases in the serum to decrease the chances of degredation even when protecting modifications (such as phosphorothioate bonds) are present. Exonuclease inactivation can be accomplished by heat inactivatation at 65°C (instead of 56°C) for 30 minutes. The half life of such an antisense oligo will be dependent on the target transcript, the cell type, and the antisense construct, resulting in no set average for this number. There are reports of antisense oligos lasting 24 hours in vivo (mice).