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We consider DNA oligomer duplex production and delivery an "add-on" to the service-value chain based on our unmatched capability to produce high quality ssDNA oligos up to 220 nts.

Our dsDNA oligonucleotide standard service provides for un-cloned and linear DNA fragments. The quantities delivered allow for a wide range of downstream applications/experiments like cloning, crystallization, etc.. at best value.

Just to avoid any potential misconception concerning the production technique applied, building dsDNA by adding complementary base pairs step by step is not possible. The method of choice consists in synthesizing two ssDNA oligos separately and align them to form a duplex via complementary base pairing. This drives the formation of more or less stable duplexes/dsDNA.

What you need to know to design your duplex/dsDNA:

  • Best duplex formation is achieved if sense and antisense oligos are 100% complementary. We do allow for wobble positions/randomized stretches and/or partially non-complementary stretches to create "overhangs" at both ends. However, be aware that the stability of the resulting duplexes and their Tm will be reduced;
  • The responsibility of defining/specifying the sequence of both strands (sense and antisense) is yours. We will ensure to deliver what you order at top quality but without unsolicited interfering into your designs;
  • Unless otherwise specified, we will produce your duplex/ds DNA with a hydroxyl group, both at the 5’ and at the 3’ end. If you require a phosphate group at either end, you can choose it as a 5’ or 3’ modification.

Our duplex DNA service includes

  • Synthesis, purification and QC of 2 complementary DNA oligonucleotides up to a length of 220 nts;
  • Equimolar mixing of individually QCed DNA oligos (analytical HPLC and Mass Check);
  • Annealing of the two oligos, formation of the respective duplex DNA, and "freezing" of the ds-status as dried down deliverable;
  • QC of ssDNA by ESI-ToF mass spectrometry;
  • Providing recommendations/protocol to re-dilute, re-anneal and use the delivered dsDNA oligos.

A full list of standard modification is available below:

Fluorescent Modifications

Concentrations available: 0.5 to 200 nmol
Purification available: HPLC

Non-Fluorescent Modifications

FAQ – you ask, we answer


While some manufacturers state that re-annealing of complementary DNA oligonucleotides is generally not necessary, we recommend to go through the process of duplex formation after having dissolved the delivered ds oligonucleotide prior to your experiments applying a suitable protocol.

For your convenience, we recommend to follow our guidelines prepared for download.


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 dsDNA/duplex DNA.
  2. Sequence of the dsDNA/duplex DNA 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 (


Yes, they are as follows:


This depends on the complexity (length, base composition, modifications) of your requested molecule, as well as on the application desired. Failure sequences may be generated both during and post-synthesis. Due to the nature of synthesis chemistry (coupling efficiency < 100%) and/or post-synthetic modification procedures, there will remain failure sequences (n-x), free modifiers and non-labeled products, respectively, in the "crude" unpurified product.

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


The expected average in-house turnover time for dsDNA 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, of course, may result in a delay.


The label on the dsDNA/duplex DNA tube shows basic information like oligo name, name of person who ordered, DLP sequence including modifications, oligo ID, amount of DNA (OD260 and nmol), Tm, and molecular weight.

In addition, you will receive a synthesis report containing more detailed information on the physical-chemical properties of the oligo, such as base composition, base count, purification grade, amount of DNA (OD260 and nmol), Tm and molecular weight. dsDNA/duplex DNAs are HPLC purified by default and you will also get a printout of the preparative chromatogram.

While each and every oligo produced and delivered is characterized by either MALDI- or ESI-ToF before release. Mass-Check documentation/spectra will only be provided if requested at time of order placement. Additional charges may apply.


To gain a maximum shelf life for oligonucleotides, samples should generally be stored dehydrated at ≤ -15 °C in absence of light. Under the mentioned conditions, samples are stable for at least 6 months. In case of a longer storage period, oligos should be pretested for molecular integrity prior to experimental use. If stored frozen at –20 °C or –70 °C, it will remain stable for several months. Repeated freeze-thaw should be avoided, as this will denature the dsDNA. Moreover, the dsDNA stability in solution depends on the pH. Dissolving dsDNA into acidic solutions may result in its degradation. Therefore, avoid the use of unpurified distilled water as a diluent, since solution pH may be as low as 4-5. In addition to what above advised, we recommend that you minimize the exposure of modified dsDNA/duplex DNA – especially if fluorescently labelled - to light, to avoid any bleaching effect.

Moreover, we recommend storing dye-labelled dsDNA/duplex DNA highly concentrated and not in working dilutions, if you are not planning to use it within 24 hours. The higher the dilution factor, the faster the fluorescent activity fades away. Therefore, try to store highly concentrated aliquots frozen, thaw them only once, dilute them just before you use the probe and store the aliquots at 4 °C in the dark.


There is a normal degree of variation in the appearance of the supplied dry pellets. Variation in appearance per se does not indicate a quality defect. In general, appearance of unmodified and dye-labeled dsDNA pellets may vary from powdery to hyaloid. The color of unmodified dsDNA pellets may range from transparent over off-white and yellowish to tan. The pellets of labeled dsDNA are colored according to the dye attached.