Long oligo synthesis

  • Superior quality and yield
  • Unmatched DNA synthesis length, up to 300 bases
  • RNA synthesis up to 120 bases
  • Very competitive pricing
  • Reliable service and fast turnaround times


Our B-pure Oligonucleotide Synthesis protocol produces custom synthesis of affordable, high-quality long oligos up to 300 bases. For oligonucleotides longer than 80 bases the B-pure protocol is the standard synthesis method.

Long oligos can be ordered in our webshop by entering your DNA sequences (up to 300 bases!) or RNA sequence (up to 120 bases).

Alternatively long oligos can be ordered by email. Download our excel orderform for ordering by email or use it to upload multiple sequences in our webshop.

Long oligos for medium and high-throughput applications oligos can be ordered in plates. No additional charge for orders containing more than 48 oligos per plate. More information about synthesis in plates.

Modifications can be incorporated in long oligos either during (direct) or after (indirect) synthesis.


You can choose from a wide variety of modifications. Please contact us for more information.

Coupling efficiency relates to the final amount of full length sequence after synthesis of your oligonucleotide.  Oligonucleotide synthesis is the step-wise addition of nucleotide residues to the 5'-site of the growing chain until the desired sequence is completed. Each addition of nucleotide residues is called a synthesis cycle. The coupling efficiency defines the efficiency of each synthesis cycle. 

By using the B-Pure synthesis protocol we can achieve an average coupling efficiency >99.5% for ideal sequences through an entire 300 base synthesis reaction.

A coupling efficiency of 99% or 98% seems to be very good, but on closer examination the full-length yield is only half for a 40 mer! For a 300 mer this will result in a crude yield of less than 5%, which is not acceptable. As demonstrated in the figure below, the only way to synthesize longmers up to 300 bases with an appreciable yield of full length material (>30%) is to have a coupling efficiency of more than 99.5%.



When an oligo increases in length, the total yield decreases. Furthermore, the likelihood of building loops, hairpins or other secondary structures during synthesis increases. This leads to a higher presence of deletions in the oligonucleotide sequence, which makes a PAGE purification strongly recommended for oligos over 50 bases. With PAGE purification you can reach a purity between 97% to 99.9% depending on oligo sequence and structure.

>More about purification