MISSION® siRNA

Custom Options and Services

Can you make siRNA with 5' or 3' tags?
Yes, Sigma-Aldrich offers custom siRNA ordering, with several available 5' or 3' modifications. If you do not see the 5' or 3' modification you are interested in, please email us at MISSIONRNAi@sial.com, or contact your local sales representative. Please see our website: sigma.com/customsirna.
 
Can you make siRNA with modified bases?
Yes, Sigma-Aldrich offers custom siRNA ordering, with several available internal modifications. If you do not see the internal modification you are interested in, please email us at MISSIONRNAi@sial.com, or contact your local sales representative. Please see our website: sigma.com/customsirna.
 
Could you please provide the function/reason why I would use the modifications you offer?
Please see explanations below.
Amine: These mods are used to either block the respective end or to attach an NHS-ester dye which may not be available as a phosphoramidite (for direct addition to the RNA strand during synthesis) or perhaps is not compatible with the chemistry of cleaving and deprotection of the RNA.
Biotin: Similar to DNA this is typically used as an anchor or location where either a Streptavidin tagged molecule can be added, or to be used to separate from other molecules (fish).
Cyanine-dyes: Purely for detection of one of the strands via fluorescence. Used to determine transfection efficiency.
Fluorescein: Purely for detection of one of the strands via fluorescence. Used to determine transfection efficiency.
6-FAM:   (Same as Fluorescein, just an isomer instead of a mixture of the 5 and 6 isomers) Purely for detection of one of the strands via fluorescence. Used to determine transfection efficiency.
Phosphorylation: Reported to aid in the strand selection process of RNAi.
Cholesterol: Improved permeation through the cellular membrane.
Thiol: Another anchor where other molecules could be added via a S-S linkage.
Phosphorothioate linkages: Improved cellular stability against nucleases.
2'-O-Methyl bases: Improved cellular stability against nucleases and increased specificity.
LNA bases: Preferred molecule to improve specificity via the increase in Tm. (Please note, Sigma-Aldrich does not provide LNA bases).
 
Can you make the siRNA that I design?
Yes, Sigma-Aldrich offers custom siRNA ordering. Please see our website: sigma.com/customsirna.