Oligo synthesis: Custom DNA oligonucleotides

We specialize in modified oligos, fluorescent probes, long oligos and large scale oligo synthesis. The more modifications that are present in an oligo, and the longer the sequence, the more demanding the synthesis and purification. By tailoring the synthesis protocol to each specific oligo we give it the best chance of succeeding. We then use our knowledge of purification methods to produce the purest oligo possible and carry out a detailed in depth analysis. If we find anything unexpected we repeat the synthesis under optimised conditions.

We often work with our customers before ordering, suggesting modifications that will give the best results, both in the synthesis of the oligo and in subsequent biochemical experiments. Our job isn't done when we despatch oligos; we welcome customer feedback and if problems arise we make it our mission to help to find out why, suggesting changes to the oligo design that will improve the results next time.



Most of the oligos we make contain modifications, and many contain several different modifications. See the page on modified oligos.

Synthesis scale

We can synthesize oligos on the 0.2 μmol, 1.0 μmol, 15 μmol and 30 μmol scales. But if you are not sure, or if you need a specific amount of oligo, contact us and we will advise you on the best synthesis scale. Because we treat each oligo individually, and are sensitive to the particular chemistry of the oligo and modifications, we obtain the best possible quality and yields.


We usually purify oligos by HPLC. Where extra purity is required, we suggest Double HPLC purification. We also offer polyacrymide gel electrophoresis (PAGE) purification for longer oligos. If you're not sure which purification method to request, contact us and we'll be glad to discuss the best purification strategy for your oligo.


We take quality control very seriously. We analyze oligos by capillary electrophoresis (CE) and HPLC, and optionally by mass spectrometry.


We supply a data sheet with each oligo, outlining details on the oligo sequence, physical properties (molecular weight, predicted melting temperature, extinction coefficient etc.) and quality control data (concentration, and total amount of oligo sent).


We supply oligos in solution in screw-top vials. The concentration (in OD mL-1, mol dm-3 and μg mL-1) is included on the attached data sheet. Alternatively, we can adjust the concentration to a value you specify.

We can also supply oligos as freeze-dried solids, which we recommend for long-term storage.


We send oligos via DHL or TNT.