FlexiTube siRNA Premix

For optimized, one-step siRNA transfection


The FlexiTube siRNA Premix is intended for molecular biology applications. This product is not intended for the diagnosis, prevention, or treatment of a disease.
FlexiTube siRNA Premix

Cat. No. / ID: 1027420

Optimized siRNA–reagent mix; 0.75 nmol siRNA; provided in tubes


  • Save time — just add to cells and incubate
  • Efficient transfection with reduced effort
  • Consistency across multiple experiments

Product Details

FlexiTube siRNA Premix is an optimized mixture of siRNA and transfection reagent. Premixing of siRNA and reagent saves time by eliminating mixing and complex formation protocol steps. In addition, use of FlexiTube siRNA Premix removes the effort involved in estimating optimal siRNA-reagent ratios. FlexiTube siRNA Premix is available for human and mouse genes.


The ratio of reagent to siRNA in FlexiTube siRNA Premix provides highly efficient transfection and gene knockdown (see figures "  Rapid, efficient knockdown" and "  Phenotype analysis after knockdown").

FlexiTube siRNA Premix contains FlexiTube siRNA, which is designed using highly innovative and sophisticated HP OnGuard siRNA Design to deliver high potency and specificity. siRNAs are designed using neural-network technology based on a large data set from RNAi experiments. siRNA design is then checked for homology to all other sequences of the genome using an up-to-date, nonredundant sequence database and a proprietary homology analysis tool that incorporates exciting design features.

Performance guarantee

FlexiTube siRNA Premixes come with a one-time-only replacement offer. If several FlexiTube siRNA Premixes for the same target gene are ordered and at least 2 of them do not provide ≥70% target gene knockdown, QIAGEN will provide 2 additional siRNAs free of charge, once only. You will be asked to provide supporting data, demonstrating that the siRNA failed to knock down the target gene by at least 70% at the mRNA level under appropriate transfection conditions. Supporting data should include transfection efficiency data, quantitative silencing data, and data showing ≥70% knockdown of a positive control. This offer is valid for up to 6 months after the date of delivery.

See figures


With FlexiTube siRNA Premix, siRNA for your gene of interest and highly efficient transfection reagent are already premixed and provided in a single tube. FlexiTube siRNA Premix includes a specialized buffer that increases the stability of siRNA-reagent complexes. The ratio of reagent to siRNA in FlexiTube siRNA Premix is preoptimized to provide the highest transfection efficiency and gene knockdown (see figures "  Rapid, efficient knockdown" and "  Phenotype analysis after knockdown").
See figures


FlexiTube siRNA Premix is ready-to-use for cell transfection. Simply add to cells and incubate. This is a significant time and labor saving compared with a typical transfection experiment in which siRNA is diluted, mixed with transfection reagent, and then the mixture is incubated to allow siRNA-reagent complex formation prior to adding the complexes to the cells and incubating.

With FlexiTube siRNA Premix, RNAi experiments get off to a faster start, as there is no need to optimize siRNA to reagent ratio. Tedious optimization experiments involving multiple transfections are minimized or eliminated, as FlexiTube siRNA Premix provides siRNA and reagent premixed at an optimal ratio.

Multiple transfections can be performed from a single FlexiTube siRNA Premix. This reduces variability, enabling consistency across experiments and more reliable results.


FlexiTube siRNA Premix is ideal for functional genomics or pathway analysis with small numbers of gene targets.

Supporting data and figures


DesignHP OnGuard design
Target sequence providedYes
siRNA per target genevariable
Number of transfections50 standard transfections in 24-well format
Guarantee/validationfor validated siRNAs
SpeciesHuman, mouse
Scale or yield0.75 nmol


Is one able to use FlexiTube siRNA Premix for transfection of primary adherent cell types?
QIAGEN's experience using FlexiTube siRNA PreMix and transfection of primary adherent cell types is limited, but we do know that researchers have achieved excellent results with some primary cell types, for example, HUVEC cells.
FAQ ID -2268
How do I store my FlexiTube siRNA Premix?
Reconstituted FlexiTube siRNA Premix can be stored at 4°C for one month.  For storage longer than one month, it is recommended to store the reconstituted mix at -20°C.  We found that after 5 freeze-thaw cycles, the potency of FlexiTube siRNA Premixes was not affected. However, although it is not recommended, we found that storage of reconstituted FlexiTube siRNA Premix for 6 months at 4°C did not reduce the gene silencing potency compared to reference transfections.
FAQ ID -2270
Does the atypical look of the lyophilized FlexiTube siRNA Premix have a negative impact on performance?
The pellet of the lyophilized FlexiTube siRNA Premix does not look like a typical nucleic acid pellet.   The lyophilized FlexiTube siRNA Premix has a gel-like appearance.  This is the typical appearance of this product and has no impact on the quality of the material or its performance in downstream assays.
FAQ ID -2267
Do I have to order at least 4 FlexiTube siRNA Premixes?
No, there is no minimal order number for FlexiTube siRNA Premix. You can order one single FlexiTube siRNA Premix if desired.
FAQ ID -2266
Is one able to use FlexiTube siRNA Premix for transfection of primary suspension cell types?
Similar to other chemical transfection technologies, FlexiTube siRNA Premix is not recommended for the transfection of primary suspension cell types.
FAQ ID -2269
How do I submit a siRNA order by telephone or online?

FlexiTube siRNA, FlexiTube GeneSolution, FlexiTube siRNA Premix, FlexiPlate siRNA, and GeneFamily Lists siRNAs can be ordered by catalog number over the telephone.

However, to ensure accuracy, Custom siRNA Synthesis orders should be submitted in writing. Therefore you can use the HP Custom siRNA Order Form https://www.qiagen.com/products/genesilencing/customsirna/customsirnaorder.aspx?EmailOrdering=1.

Visit the RNAi Solutions page http://www.qiagen.com/products/rnai/default.aspx?r=2714 on our homepage for access to the Online Ordering Tool, and choose the order link for your product of interest.

FAQ ID -399
If I am working with a difficult-to-transfect cell type or if I obtain only weak silencing effects what can I do?
In the case of difficult cell types or weak silencing effects, it may be helpful to increase the final siRNA concentration during transfection. This can be achieved simply by using larger amounts of FlexiTube siRNA Premix for transfection.
FAQ ID -2265
Is it possible to use lower siRNA concentrations with FlexiTube siRNA Premix?
FlexiTube siRNA Premix works with minimal siRNA concentrations. To decrease the final siRNA concentration, simply use smaller volumes of FlexiTube siRNA Premix for transfection. For example, using only half of the volume given in the protocol will lead to a final siRNA concentration of 12.5 nM. Depending on the cell type, final siRNA concentrations of down to 1 nM can lead to sufficient gene silencing.
FAQ ID -2264
Has RNAi been successful using siRNA in Zebrafish and Xenopus?

Here are examples of references that describe the inhibition of gene expression by siRNA in Xenopus and Zebrafish:

FAQ ID -400