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siRNA solutions by Dharmacon™

Reliably silence gene function in any cell type

RNA interference via synthetic small interfering RNA (siRNA) is the preferred choice for fast but reliable loss-of-function studies. Broadly useful across many applications and in any cell line, siRNA offers a straightforward and widely cited technique for functional gene silencing. For over 20 years, Dharmacon has remained the most trusted name in high quality siRNA design and synthesis.

Select a predesigned siRNA product line or design your own siRNA with custom modifications.


Knockdown with confidence using a premium synthetic siRNA, chemically modified for maximum specificity.

Accell siRNA

Silence genes in difficult-to-transfect cell types without transfection or electroporation using self-delivering siRNA.


Trusted gene silencing from the longest standing siRNA guarantee on the market.

Not sure where to start?

Need help planning an RNAi experiment, choosing a transfection reagent or finding proper controls? Our expert scientific support team is here to help!

Our siRNA knockdown guarantee

The ON-TARGETplus, Accell and siGENOME siRNA lines are guaranteed* to effectively silence target gene expression by at least 75% at the mRNA level.

Lincode siRNA

Knockdown long, non-coding RNA genes with specialized siRNA, modified to ensure specificity.

Custom siRNA design

Design your own siRNA for any species on our user-friendly tool.

Reducing off-targets maximizes specificity

A successful siRNA knockdown experiment must be both effective and specific. Horizon’s SMARTselection design algorithm (used for ON-TARGETplus, Accell, siGENOME and Lincode siRNA) provides a high degree of confidence that the targeted gene will be the only one silenced.

The primary source of siRNA-mediated off-targets is the seed region (nucleotides 2-7), which uses the microRNA pathway to induce non-specific gene silencing via interactions within the 3' UTR. Incorporating comprehensive bioinformatic strategies such as seed region filters and seed frequency analysis within the SMARTselection design strategy minimizes microRNA-like off-target activity for improved specificity.


Pooling siRNA improves effectiveness

The SMARTpool (available for ON-TARGETplus, Accell, siGENOME and Lincode siRNA) combines four gene-specific siRNAs into a single reagent pool. Research has shown that pooled siRNAs:

  • Improve the likelihood of effective gene silencing
  • Minimize sequence-specific off-targeting by lowering the relative concentration of each siRNA
  • Better mimic the natural RNAi pathway
  • Reduce false negatives caused by inaccessible binding sites

Which siRNA is right for you?

Horizon offers multiple predesigned product lines across human, mouse and rat genomes. Use the table below to determine the optimal siRNA for your needs.

ON-TARGETplus siRNA Chemically modified for enhanced specificity Accell siRNA Self delivering siRNA siGENOME siRNA Cost-effective, efficient silencing Lincode siRNA Knockdown long non-coding RNA
Recommended for neuronal, suspension, primary and other difficult-to-transfect cells
Recommended transfection reagent DharmaFECT transfection reagent None required DharmaFECT transfection reagent DharmaFECT transfection reagent
Available as individual siRNA and SMARTpool formats
Guaranteed knockdown by SMARTpool and 3 of 4 siRNAs
Sense strand modifications to prevent interaction with RISC and favor antisense strand uptake
Antisense strand seed region modifications to destabilize off-target activity and enhance target specificity
Modified to facilitate cellular uptake without separate transfection reagents
Stabilizing modifications to prevent nuclease-mediated degradation
Sequence information provided with purchase
Search ON-TARGETplus Search Accell Search siGENOME Search Lincode


siRNA screening libraries

RNAi based screening using synthetic siRNA is a useful tool for understanding a disease pathway or for drug target identification. Researchers can design a custom screening library with as few as 20 ON-TARGETplus, Accell, Lincode or custom siRNA using our Cherry-Pick Library Tool, or browse our wide selection of predefined gene family and whole genome siRNA libraries.


Experimental support

Need help with a new RNAi technique? We offer live scientific support as well as an extensive collection of technical resources to help get you started!

Speak with an RNAi expert 

Our scientific support team of PhD scientists is here to help with your gene knockdown experiment.

siRNA technical resources

Posters, app notes, protocols and technical manuals for using siRNA solutions by Dharmacon to achieve reliable and efficient gene silencing.

Video: Basic siRNA resuspension

Learn the best practice for resuspending lyophilized siRNA in this short video.

siRNA by Dharmacon selection guide

Choose the optimal siRNA product line and format for your experiment

Accell siRNA silencing workflow

Experiment workflow for gene silencing with Accell self-delivering siRNA.

siRNA control recommendations

This technical note discusses the function and features of a variety of control siRNAs.

*Gene silencing guarantee applies to SMARTpool and “3 of 4 individual siRNA” formats when demonstrated to have been used under optimal delivery conditions (confirmed using validated positive control and measured at the mRNA level 24 to 48 hours after transfection using 100nM siRNA). For more information regarding the siRNA knockdown guarantee, please contact tech support.