siRNA customization has never been easier
No pre-designed product to fit your needs? Use our online design tools and extensive synthesis options to create a custom siRNA specific for your application. Numerous combinations of modifications, sizes, and purification options are available for convenient online ordering.
Preclinical scale/OEM service for synthesis of RNA and DNA at larger quantities
Order both modified or unmodified siRNAs. Patented modification patterns (ON-TARGET, ON-TARGETplus, siSTABLE, or Accell) and additional custom modifications are available.
To complement our pre-designed siRNA collections and support a broad range of RNAi experiments, our siRNA design experts can provide custom SMARTpool reagents targeting genes outside of our genomewide offerings
Design siRNAs targeting genes in non-standard species, particular splice variants or homologous regions across gene families or species.
For unmodified siRNA, the following approximate yields can be expected:
Our capabilities include a range of alternative siRNA designs to empower your RNAi research
If you are working in human, mouse or rat models, we may already have what you need as a pre-designed product: Search for your gene in the Search field found in the upper right corner.
Take advantage of our internal design experts and SMARTpool technology! Order a functionally guaranteed Custom SMARTpool for worry-free customization.
Alternative siRNA designs that we support include:
If you can't find what you need or you require additional specifications not available through online order, please request a quote.
For further assistance, please contact Technical Support.
Modified for specificity, stability or self-delivery, we have the siRNA solution.
All siRNA modifications, proprietary and other, are available through custom siRNA synthesis
The ON-TARGET modification promotes correct strand uptake by blocking the sense (passenger) strand from being taken up by the RISC process. This is a useful method for ensuring antisense (guide) strand processing. All proprietary siRNA modifications (ON-TARGETplus, Accell, siSTABLE) incorporate this sense-strand modification to promote antisense (guide) strand-facilitated silencing.
A 2006 publication demonstrates that off-target effects are primarily driven by antisense strand seed activity.1 Therefore, sense strand inactivation alone does not decrease the total number of off-target genes. ON-TARGETplus modifications account for both strands:
The ON-TARGETplus modification pattern dramatically reduces off-targets. Off-target effects induced by the indicated siRNAs were quantified using microarray analysis. For each target, three different siRNAs were used: unmodified, sense strand-inactivated, and ON TARGETplus-modified. Data shown represents genes down-regulated by two-fold or more. HEK293 cells were transfected with 100 nM siRNA using 0.2 µL of DharmaFECT 1. Data was analyzed at 24 hours.
1 Jackson, A.L. et al. "Position-specific Chemical Modification Increases Specificity of siRNA-mediated Gene Silencing." RNA 12.7 (2006) 1197-1205.
Neonatal rat ventricular myocytes were incubated with 1 µM Accell Green (A; Cat# D-001950-01) or Red (B; Cat# D-001960-01) Non-targeting siRNA for 72 hours in Accell delivery media (Cat# B-005000). Nuclei were stained with DAPI (blue). Labeled control uptake showed diffuse cytoplasmic localization in nearly all cells.
The bar graph indicates the level of gene silencing achieved with Accell GAPD Control siRNA (Cat# D-001930-03) and Pool (Cat# D-001930-30) control reagents when used with neonatal rat ventricular myocyte (NRVM) media or Accell delivery media.
Myocytes were prepared as described in Maass AH & Buvoli M. Cardiomyocyte preparation, culture, and gene transfer. Methods Mol Biol. 2007;366: 321-30. mRNA expression was determined by QuantiGene branched DNA assay (Panomics).
Conventional siRNA is degraded within minutes in serum-containing environments, making in vivo use of siRNA problematic. This graph presents evidence that the siSTABLE modification pattern dramatically extends the half-life of siRNA in the presence of 100% human serum as compared to Stealth RNAi (Invitrogen).
Accell siRNA also includes these stability-enhancing modifications, as well as providing delivery to difficult-to-transfect cells without a transfection reagent.
Dharmacon offers a broad portfolio of dye modifications for fluorescent labeling of your custom siRNA and RNA oligonucleotides.
Some of the dye options listed in the above tables will produce higher oligo yields than others. For assistance in choosing the most appropriate dye label for your application, please contact Technical Support. You can also request a quote online if you already know that an alternative dye will be required for your experiments.
Alexa Fluor® is a registered trademark of Invitrogen Corporation.
In addition to fluorescent dyes, we offer a broad portfolio of other chemical modifications that can also be applied to both siRNA and single-strand RNA.
For information on our specialized modification patterns for reducing off-targets, self-delivery and nuclease resistance, view the Proprietary siRNA tab.
siRNA can be modified at either end, on either strand. Multiple modifications are also available but availability may be dependent upon sequence or other factors. Please contact Technical Support for more information
Standard modifications for single-strand RNA can also be applied to siRNA by request. Please contact Technical Support to inquire about additional modifications or options for your siRNA, or request a quote now.
We routinely achieve 80-85% purity for unmodified siRNA strands without additional purification.
However, purification may be recommended when chemically synthesized siRNAs are:
Please contact Technical Support for information regarding recommendations for purification or purity estimates for unpurified material.
Partner with the industry leader in RNAi technologies for the highest quality in vivo -ready RNAi reagents.
We want to ensure your in vivo experiments have the best chance of success. To assist you in your experimental planning, we offer the following options and guidance:
The ON-TARGET modification promotes correct strand uptake by blocking the sense (passenger) strand from being taken up by the RISC process. This is a useful method for ensuring antisense (guide) strand processing.
All proprietary siRNA modifications (ON-TARGETplus, Accell, siSTABLE) incorporate this sense-strand modification to promote antisense (guide) strand-facilitated silencing.
Description: Fluorescein is often used in fluorescence experiments to demonstrate the kinetics of folding or substrate binding. Fluorescein is also used as a donor to track optimal changes related to folding or substrate binding to intermolecular interactions.
Reference: Science 266: 785-789 (1994), EMBO J. 17: 2378-2391 (1998)
For more information please contact:Technical Support
00800-222 00 888
+44 (0) 845 3 63 04 25 (UK / EMEA)
Description: TAMRA is a strongly absorbing dye with a wide variety of applications. This modification is coupled from the 5'- or 3'-end of an oligonucleotide to either the 5th or 6th position of the dye.
References: Nucl. Acids. Res. 24: 4535-4542 (1996), Biochem. 39: 14487-14484 (2000)
Modification Code: Cy3
Unit Molecular Weight: 507.59 g/mol
Cy3 Extinction Coefficient: 136,000
Excitation/Emission Max: 547 nm/563 nm
Modification Code: Cy3-3’
Unit Molecular Weight: 800.85 g/mol
Modification Code: Cy5
Unit Molecular Weight: 533.63 g/mol
Cy5 Extinction Coefficient: 250,000
Excitation/Emission Max: 646 nm/662 nm
Modification Code: Cy5-3’
Unit Molecular Weight: 826.88 g/mol
Modification Code: Cy5^5
Unit Molecular Weight: 633.75 g/mol
Cy5.5 Extinction Coefficient: 209,000
Excitation/Emission Max: 688 nm/707 nm
Modification Code: Cy5^5-3’
Unit Molecular Weight: 927.00 g/mol
What is an NHS Ester?
An NHS ester is a reactive group found on the dye that provides the functionality for labeling amino groups found on the oligonucleotide.
Some DyLight dyes are available as phosphoramidites (our standard dyes), and others as NHS esters (our non-standard Alexa alternatives). If applicable, we recommend DyLight dyes as a first choice since this form is most compatible with our 2'-ACE RNA synthesis chemistry and will therefore be more likely to produce higher yields.