3D-model of DNA
The DNA sequences produced are also called oligonucleotides. These are widely used for disease identification, for the manufacture of oligonucleotide-based drugs, and for several other medical and biotechnological applications.
The high demand for oligonucleotides therefore requires an efficient automated method for their chemical production.This process relies on phosphoramidites, which are chemical compounds that have the disadvantage of being unstable unless stored at the ideal -20 degrees Celsius.
Instruments used for DNA synthesis are not able to cool down the phosphoramidites, and consequently it is unavoidable that some of them degrade after being added to the instrument.
Avoiding unwanted degradation of important ingredients
Professor Kurt Gothelf and Professor Troels Skrydstrup are each heading a research group in organic chemistry, which have worked together to develop a relatively simple but efficient technology where the production of phosphoramidites can be automated and integrated directly into the instrument for DNA synthesis.
This avoids both the manual synthesis of these, which normally would take up to 12 hours, as well as the problem of storing unstable phosphoramidites. Gothelf’s group has contributed with their expertise in automated DNA synthesis and Skrydstrup’s group has contributed with their know-how with chemical reactions that take place in continuously flowing liquids (flow chemistry).
The results have just been published in the journal Nature Communications. In the method of producing phosphoramidites, nucleosides (starting materials) are flushed through a solid material (resin), which can potentially be fully integrated into an automated process in the instrument for DNA synthesis. The resin ensures that the nucleosides are rapidly phosphorylated, whereby the nucleosides are converted to phosphoramidites within a few minutes. From the resin, the phosphoramidites are automatically flushed on to the part of the instrument which is responsible for the DNA synthesis.
This avoids the degradation of the phosphoramidites, as they are first produced just before they are to be used (on-demand), in a faster, more efficient flow-based way that can potentially be automated and operated by non-chemists.
Alexander F. Sandahl et al, On-demand synthesis of phosphoramidites, Nature Communications (2021). DOI: 10.1038/s41467-021-22945-z