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High quality and cost-effective custom siRNA sequence synthesis available for your unique sequence or by using our in-house design service, utilizing the Rosetta Design Algorithm. Choose from a wide range of modifications, purifications and quantities to tailor to your specific needs.
(Provide the gene symbol, refseq and species, or transcript to target for design, and the # of designs needed. Our bioinformatics dept. will provide siRNA sequences designed by our Rosetta design algorithm, and will return the results to you by email within 3 business days).
For siRNA designed by Sigma® Life Science, we guarantee that 2 out of 3 siRNA per gene will achieve knockdown of ≥75%.
With a capacity to synthesize over one million siRNA oligos per year, Sigma offers reliable delivery times, no matter how many oligonucleotides you order.
Our RNA synthesis relies on the use of fast deprotection ribonucleoside phosphoramidites protected at the 2' position by a tert-butyldimethylsilyl (TBDMS) group and, at the 3' position, by a phosphoramidite.
RNA synthesis and deprotection are performed using Sigma's proprietary technologies ie. Ultra Fast Parallel Synthesis (UFPS) and Ultra Fast Parallel Deprotection (UFPD). The use of these technologies means higher coupling efficiency and faster deprotection, resulting in higher quality synthesis and faster turn-around times.
UNA (Unlocked Nucleic Acid) Modification
UNAs (Unlocked Nucleic Acid) are helix destabilizing, non-nucleotide analogues of RNA in which the bond between the C2’ and C3’ atoms is not present (see Figure 1). Incorporation of UNA results in considerable reduction in the RNA:RNA duplex melting temperature (Tm) while maintaining an A-form helical structure1.
Figure 1. General structure of UNA
Like LNA, UNA enables fine tuning of duplex thermodynamic stabilities. Their antipodal structural characteristics make UNA and LNA complementary with respect to effect on binding affinity towards a DNA or RNA target: Tm is decreased by 5-10°C per UNA monomer2; Tm is increased by 3-10°C per LNA monomer.
Pasternak, A. and Wengel, J. (2011) Unlocked Nucleic Acid – an RNA Modification with Broad Potential. Org. Biomol. Chem., 9. 3591-3597.
Bramsen, J.B., laursen, M.B., Nielsen, A.F. et al. (2009) A large-scale chemical modification screen identifies design rlues to generate siRNAs with high activity, high stability and low toxicity. Nucleic Acids Res., 37, 2867-2881.
Kenski, D.M., Cooper, A.J. et al (2010) Analysis of acyclic nucleoside modifications in siRNAs finds sensitivity at position 1 that is restored by 5’-terminal phosphorylation both in vitro and in vivo. Nucleic Acids Res., 38, 660-671.
Narendra Vaish, Feng Chen. (2010) Improved Specificity of Gene Silencing by siRNAs Containing Unlocked Nucleobase Analogs. Nucleic Acids Research, 39-5 1823-1832.
Yang, X. et al. Gene Silencing Activity of siRNA Molecules Containing Phosphorodithioate Substitutions. ACS Chem Biol. 2012 Apr 18. [Epub ahead of print]
siRNA Literature for Download