An Overview of Phosphoramidites for Oligonucleotide Synthesis

Phosphoramidites are widely used building blocks in solid-phase oligonucleotide synthesis. During a synthesis cycle, a protected nucleoside phosphoramidite is coupled to the growing chain, followed by oxidation or sulfurization and removal of the temporary protecting group. Repeating this sequence allows the controlled assembly of DNA, RNA and chemically modified oligonucleotides.

A typical phosphoramidite contains a nucleoside or another functional building block, protecting groups that control reactivity, and a phosphoramidite moiety used for coupling. DNA phosphoramidites commonly represent protected forms of dA, dC, dG and dT. RNA monomers require additional protection of the 2'-hydroxyl group, such as TBDMS, while 2'-O-methyl, 2'-O-MOE and 2'-fluoro monomers are used when a defined chemical modification is required.

Modified building blocks extend the function of an oligonucleotide beyond its natural sequence. LNA and ENA monomers can alter conformational properties and hybridization behavior. Amino, thiol, biotin, cholesterol and spacer modifiers can introduce reactive groups, labels or structural spacing. Because abbreviations vary across suppliers, the full product name, CAS number where available, and chemical structure should be checked together before ordering.

Purity is important, but it should not be the only purchasing criterion. Identity confirmation, water content, residual solvent control, phosphorus-related impurities, packaging and storage conditions may affect performance. The appropriate documentation depends on the product and development stage. Customers should discuss available analytical methods and certificates with the supplier instead of assuming that every phosphoramidite is tested using the same protocol.

Many phosphoramidites are sensitive to moisture and prolonged exposure to unsuitable temperatures. Packaging should support the intended use quantity and minimize repeated opening. Storage and transport requirements must follow the product specification and safety documentation. After receipt, the material should be checked against the label and certificate before it is introduced into a synthesis workflow.

When requesting a quotation, provide the complete English name, CAS number or structure, required purity, quantity and any special documentation needs. For custom monomers, include the desired protecting-group strategy and intended application. Clear technical information at the inquiry stage helps the supplier distinguish closely related products and provide a more reliable evaluation.

Call to action: Looking for a listed product or a custom structure? Send us the product name, CAS number or structure, purity, quantity and destination. Contact Orihar for availability and quotation.