siRNA designed and modified for greater specificity

ON‑TARGETplus siRNA reagents reduce off-targets utilizing a patented dual-strand modification, while still providing guaranteed gene silencing of human, mouse and rat gene targets. This unmatched potency and specificity make ON‑TARGETplus siRNA the premium choice for optimal knockdown and reduced off-targets. Simply search for your gene of interest and choose from the available product formats and quantities.

Start your gene search


  • We now offer a 2 nmol size when purchasing pre-designed ON‑TARGETplus or siGENOME siRNAs for human, mouse, or rat.
  • Off-targets reduced by up to 90% compared to unmodified siRNA.
  • Guaranteed silencing by SMARTpool and 3 of 4 individual siRNAs (See Product Formats tab).
  • Sequence information provided with siRNA purchase.

A two-stranded mechanism requires a two-stranded solution

Our scientists and collaborators demonstrated in 2006 that siRNA off-targets are primarily mediated by antisense seed-region interactions, initiating the development of a dual-strand modification pattern to effectively reduce off-targets:

  • Sense strand is modified to prevent interaction with RISC and favor antisense strand uptake.
  • Antisense strand seed region is modified to destabilize off-target activity and enhance target specificity.

Jackson et al., Position-specific chemical modification increases specificity of siRNA-mediated gene silencing. RNA12(7), 1197-1205 (2006).

Product Formats


  • A mixture of 4 siRNA provided as a single reagent; providing advantages in both potency and specificity. siGENOME and ON‑TARGETplus are guaranteed to silence by 75% or better.

Set of 4:

  • A convenient option for purchasing aliquots of all 4 individual siRNAs targeting a single gene. Three of four siGENOME and ON‑TARGETplus siRNAs are guaranteed to silence by 75% or better.

Set of 4 Upgrade:

  • Discounted price on the Set of 4 based on a concurrent or prior purchase of the SMARTpool reagent for the same gene.

Individual siRNAs:

  • Select 1, 2, 3 or 4 individual siRNAs per gene.

Our siRNA knockdown guarantee

siGENOME and ON‑TARGETplus siRNA reagents (SMARTpool and three of four individual siRNAs) are guaranteed to silence target gene expression by at least 75% at the mRNA level when 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).

Note: Most siGENOME and ON‑TARGETplus siRNA products are highly functional at 5 to 25nM working concentration.

Ordering Guidelines

Approximate # reactions (wells) at 25 nM siRNA concentration (assuming no loss from pipetting)

96-well plate
(100 uL total reaction volume)
24-well plate
(500 uL total reaction volume)
12-well plate
(1000 uL total reaction volume)
2 800 160 80
5 2000 400 200
10 4000 800 400
20 8000 1600 800

Product Line Selection

Which siRNA is right for you?

Dharmacon offers four complete pre-designed product lines across human, mouse and rat genomes. Use the table below to assist you in determining the right siRNA product line for your needs.

Cost-effective, efficient silencing High specificity for reduced off-targets + efficient silencing Highly specific knockdown of long noncoding RNA (lncRNA) Target silencing in difficult-to-transfect cells
siGENOME siRNA ON‑TARGETplus siRNA Lincode siRNA Accell siRNA
Pre-designed for Human, Mouse and Rat protein-coding genes + + +
Pre-designed for Human and Mouse long noncoding RNA (lncRNA) +
Recommended for transfectable mammalian cells in culture + + +
Recommended for neuronal, suspension, primary and other difficult-to-transfect cells +
Recommended transfection reagent DharmaFECT transfection reagent DharmaFECT transfection reagent DharmaFECT transfection reagent None required
Available as SMARTpool reagent + + + +
Available as four individual siRNAs + + + +
Guaranteed knockdown by SMARTpool and 3 of 4 siRNAs + +
Sense strand is modified to prevent interaction with RISC and favor antisense strand uptake Selective application when thermodynamic analysis indicates it necessary for favorable antisense RISC loading + + +
Antisense strand seed region is modified to destabilize off-target activity and enhance target specificity + +
Modifications to facilitate cellular uptake without separate transfection reagents +
Stabilizing modifications to prevent nuclease-mediated degradation +
Sequence information provided with purchase + + + +

Supporting Data

ON‑TARGETplus modifications reduce the overall number of off-targets and pooling reduces them even further

heatmap boxplot otp

Panels (A) and (B) are representative examples of off-target signatures with and without application of ON‑TARGETplus modifications to (A) a single siRNA and (B) a SMARTpool reagent. Green bars indicate genes with 2-fold or more reduction of expression when treated with the indicated siRNA reagent.The ON‑TARGETplus modifications reduced the off-targets when compared to unmodified siRNA. Pooling of siRNA and the ON‑TARGETplus modification pattern independently, and in combination, provide significant reduction in off-target gene silencing. Panel (C) represents quantitation of off-targets (down-regulated by 2-fold or more) induced by the indicated siRNA reagents targeting 10 different genes (4 siRNAs per gene or a single SMARTpool reagent). Off-targets were quantified using microarray analysis (Agilent) then compiled. Each shaded box represents the middle 50% of the data set. Horizontal line in box: Median value of the data set. Vertical bars: minimum and maximum data values.

Only the ON‑TARGETplus modification pattern addresses both siRNA strands for premium silencing

otp modification pattern

The ON‑TARGETplus dual-strand chemical modification begins with the sense (passenger) strand being blocked from RISC uptake to favor antisense (guide) strand loading and reduce passenger strand-induced off-targets. However, the majority of siRNA off-targets are driven by the seed region of the guide strand. ON‑TARGETplus is modified within its seed region to destabilize miRNA-like activity and improve specificity to the desired target for potent knockdown.

ON‑TARGETplus siRNA dual-strand modification pattern reduces off-targets

otp reduces off-target effects

A 2006 publication demonstrates that off-target effects are primarily driven by antisense strand seed activity†. Therefore, sense strand inactivation alone does not decrease the total number of off-target genes.
ON‑TARGETplus modifications account for both strands:

  • Sense strand is modified to prevent interaction with RISC and favor antisense strand uptake
  • Antisense strand seed region is modified to minimize seed-related off-targeting

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.