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RhodaPhos® Phos Reagent – Essential Component of Oligonucleotides

Critical for Healthcare Applications

Synthetic oligonucleotides are short chain nucleic acids of a specific sequence. They are typically manufactured by solid phase synthesis using phosphoramidite building blocks derived from either 2’-deoxynucleosides (DNA), ribonucleosides (RNA) or chemically modified nucleosides (for example LNA). The primary phosphorus reagent used to make the phosphoramidites is 2-cyanoethyl-N,N,N’,N’-tetraisopropylphosphorodiamidite (RhodaPhos® Phos Reagent). Phos Reagent must be extremely pure as any impurities will be amplified during the multiple cycles required to build the oligonucleotide one block at a time.


Synthetic oligonucleotides have been investigated as potential therapeutics for more than three decades. The modalities studied are numerous and include antisense oligonucleotides, siRNA, LNA, saRNA and miRNA. With an increased number of drug approvals, many more in late stage clinical trials with indications including both rare and common diseases it appears that the technology will imminently deliver on some of its promise.(1) This progress was highlighted by the approval of Novartis’ Leqvio® (inclisiran), a cholesterol lowering siRNA drug by the European Commission in December 2020.

The onset of the pandemic in early 2020 led to rapid development of diagnostic tests for coronavirus, synthetic oligonucleotides have a role to play here too. Several different technologies have roles to play in testing, but the gold standard is RT-qPCR.(2) The RNA from a SARS-CoV-2 sample is converted to its complementary DNA sequence by reverse transcription (RT) and then the DNA is amplified by the quantitative polymerase chain reaction (qPCR). This method enables detection of very small amounts of virus with a very high accuracy. The reagents required for a RT-qPCR test include target specific DNA primers and probes which are synthetic oligonucleotides.(3)


RhodaPhos® Phos Reagent is a commercial scale, very high quality phosphorus reagent with a well-defined and controlled purity / impurity profile. To learn more about other specialty phosphorus products, please refer to the Solvay offering at Strem or the Solvay website.

Please contact for details on the product mentioned in this blog.



  1.    J Biol Chem., 2021, Feb 15: 100416.
  2.    Nature, 2020, 583, 506-509.
  3.    Int. J. Mol. Sci., 2020, 21(8), 3004.


Featured Product:

97-0695: 2-Cyanoethyl N,N,N',N'-tetra(i-propyl)phosphorodiamidite, min. 98% [RHODAPHOS® PHOS REAGENT] | CAS: 102691-36-1


Related Products:

High Quality Phosphorus Products: Products sold in collaboration with Solvay

Phosphorus Ligands and Compounds Booklet




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