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metabion offers proven knockdown solutions for gene silencing: we consider the production and delivery of duplex RNA like small interfering RNAs as an "add-on" to our service-value chain based on our unrivaled ability to produce high quality ssRNA oligos.

In most cases, double-stranded RNA (dsRNA) is used for small interfering RNA (siRNA) allocations.

siRNAs are well studied in the RNA interference (RNAi) pathway, where they regulate the expression of specific genes, whose mRNA bears complementary nucleotide sequences. In this context, siRNAs function by causing the disruption of complementary mRNAs, resulting in no translation. siRNAs also act in RNAi-related pathways, like in antiviral mechanisms or in shaping the chromatin structure of a genome. The complexity of these pathways is only now being elucidated. However, synthetic siRNAs have already become an important tool to gene validation or drug targeting as, at least in principle, any gene can be knocked down by a synthetic siRNA.

siRNAs, sometimes known as short interfering RNAs or silencing RNAs, are a class of double-stranded RNA molecules, 20-30 base pairs in length. siRNAs have a well-defined structure: short dsRNAs with phosphorylated 5' and hydroxylated, two nts overhanging 3' ends.

"Classic" siRNA design

Our standard siRNA/duplex - Portfolio

Our Portfolio covers the “classic siRNA style” as follows:

  • Fixed price/duplex based on length-independent delivered quantities from 10-200 nmol for 11-40mer duplexes;
  • 3´ DNA overhangs (dTdT are the most common) up to 2 nts without extra charge. Total length per ssRNA/RNA-DNA chimera must not exceed 40 nts each nor be shorter than 11 nts;
  • 100% HPLC purification as well as QC by Mass-Check of ssRNA for best quality;
  • Dry shipping conditions. Dissolving instructions for best duplex formation can be downloaded here
  • Average in-house turnover 5-10 working days (freight forwarders delivery time not included) and refer to our standard portfolio. In terms of "counting" working days, orders placed past 3 pm CET/CEST are considered to be next day's order.

Additionally, we offer a seasoned selection of suitable backbone and/or base modifications, which can be introduced internally and/or at both ends (3´ and/or 5´). Among these are:

2'-F, 2'-OMe, 2-Aminopurine, 5-Fluoro-dU, 5-Me-dC, 7-deaza-dG, PTO.

Please inquire!

The advantage of using such modified siRNAs are:

  • siRNA stability and base-pairing/hybridization affinity properties;
  • nuclease resistance, RNA biodistribution and cellular uptake;
  • potency and specificity of silencing;
  • siRNA immunogenicity.

FAQ – you ask, we answer


There are two ways of ordering:

  1. The preferred way is order transmission through our Web Order Portal for most convenient online shopping (please refer here for further details).
  2. You can order by sending us an e-mail at with our pre-formatted excel order file as attachment. Download respective Order Form.

When you write your e-mail, please make sure to include the following required information in the excel template:

  1. Name of the siRNA/s.
  2. Sequence of the siRNA/s in 5’-3’ orientation. 
  3. Yield range.
  4. Purification required.
  5. Delivery form (dry/in water/buffer + concentration).
  6. Modifications.

If you are a new customer, please additionally provide us with:

  1. Your shipping and billing address.
  2. Any other information like Purchase Order number, VAT number (VAT only for customers resident in the EU), etc.

In case you choose to transmit orders via e-mail using your own format(s), we need to alert you that above mentioned information in bold print is obligatory for processing your order. Due to extra efforts necessary for individual order format transfer into our system, order processing will take longer as compared to preferred web orders and pre-formatted e-mails. Please note that only files updated to the latest excel/word version (e.g. .xlsx or .docx) are accepted.

How can you convert files to newer formats?
Open the file in a recent Office program and save the file in a newer format. For this go to “File” → “Save as” and choose the newer format from the “Save as type” dropdown menu.

If you want to connect your eProcurement System with our Web Order Portal (e.g. OCI - Open Catalog Interface), please simply contact our Customer Service (


You may want to consider the following:


Given the use of siRNA oligos in cells and in vivo, high purity is essential.

High pressure liquid chromatography (HPLC) purification is standard (no additional charge) for siRNAs. For applications in cells and in vivo, we recommend an additional Size Exclusion Chromatography (SEC) purification. This is a purification that removes salts and other small molecules, whose quantity and/or quality can be toxic for cells.


Unless requested, siRNA are synthesized with neither 3´nor 5´ phosphate. Both, the 5´and the 3´-end will carry a Hydroxyl-group. The 5´ phosphorylation of both strands is available as a modification at additional charge.


The expected average in-house turnover time for siRNAs is 5–10 working days. Please note that we perform strict quality controls on each and every oligo. In case one or more oligos do not pass our quality control, they will need to be resynthesized. This may, of course, result in a delay.

In terms of "counting" working days, orders placed past 15:00 (Munich time) are considered to be next day's order.


All oligonucleotides, whether single-stranded or double-stranded oligos, are provided as dried pellets and shipped at ambient temperature. While being stable at room temperature for 2–4 weeks, they should be placed at –20 °C or at lower temperature upon receipt.


The label on the siRNA tube shows basic information like oligo name, name of person who placed the order, siRNA sequence including modifications, oligo ID, amount of RNA (OD260 and nmol), Tm, and molecular weight.

In addition, you will receive a technical data sheet containing more detailed information on the physical-chemical properties of the oligo, such as base composition, base count, purification grade, amount of RNA in nmol, Tm and molecular weight. Additionally, you will also receive a hard copy of the Mass-Check documentation/spectrum of each single strand of the duplex. The following terminology is used for differentiating between offered QC options including respective documentation coverage in our order forms and on supporting documents delivered with the products:

Mass Check
Standard quality control performed on each and every oligo. Either MALDI- or ESI-ToF, subject to the "nature of the oligo", and metabion internal procedures. This service is free of charge and the Mass Check spectrum will be provided.

Explicitly ordered and performed MALDI-ToF check. Product delivered with MALDI-ToF spectra. Additional charges apply.

Explicitly ordered and performed ESI-ToF check. Product delivered with ESI-ToF spectra. Additional charges apply.


While some manufacturers state that re-annealing is generally not necessary, we do recommend to re-anneal the dissolved duplex using a suitable protocol. For your convenience, we recommend to follow our guidelines prepared for download.


RNA duplexes are significantly more resistant to nucleases than a single strand RNA oligonucleotide. However, maintaining sterile, RNAse free conditions is always recommended as a precaution. Dried pellets are stable at room temperature for 2–4 weeks, but should be placed at –20 °C or –80 °C for long term storage. Under these conditions, dry RNA is stable for at least one year. If you want to store your RNA in solution re-suspend the delivered pellet in an RNAse-free solution buffered at pH 7.4 – 7.6 and store at –20 °C or less. We recommend that RNAs are re-suspended at a convenient stock concentration and stored in small aliquots to avoid multiple freeze thaw cycles.