Oligonucleotide conjugation reactions are predominantly carried out using a nucleophilic group on the oligonucleotide to attach to an electrophilic group on a tag or support. Formylindole, a nucleoside analogue used to introduce aldehyde groups within an oligonucleotide or at the 5' terminus are an attractive electrophilies fro bioconjugation. For the incorporation of an aldehyde functional group into an oligonucleotide, its reactivity often necessitates carrying it through solid-phase synthesis in protected or otherwise masked form, thus requiring one or more post-synthetic unmasking transformations. Saito and co-workers1 reported that an aldehyde can be incorporated directly using a 3-formylindole nucleoside phosphoramidite via solid-phase nucleic acid synthesis. The electron-donating indole ring offered some stabilization of the aldehyde while retaining enough electrophilic character to allow conjugation with hydrazine derivatives to introduce various post-synthetic modifications into the oligonucleotides. Formylindole modified base also serve as a mimic of universal nucleoside in DNA duplexes to form less stable complexes compared to unmodified oligonucleotides. Each formylindole modification reduces Tm by 7-10° C.

Contact Bio-Synthesis for formylindole modified oligonucleotide synthesis.

Product Information


Product Name:

Formylindole Oligonucleotide Modification


Modified Base, Aldehyde Modificaiton

Chemical Formula:


Exact Mass:


Formula Weight:



Bio-Synthesis Inc. Oligo Structure



Delivery Format:


Shipping Conditions:

Room Temperature

Storage Conditions:

-20°C To -70°C
Oligonucleotides are stable in solution at 4°C for up to 2 weeks. Properly reconstituted material stored at -20°C should be stable for at least 6 months. Dried DNA (when kept at -20°C) in a nuclease-free environment should be stable for years.