Notes on the Calculator for Suspension of Dry Single-stranded Oligonucleotides

Oligonucleotides are often supplied dry; briefly centrifuge tubes to ensure that the dried oligonucleotide is at the bottom of the tube.The specification sheet provided by oligonucleotide manufacturers often contains the following information:

• nmoles synthesized
• mass amount synthesized
• OD₂₆₀ units synthesized

The following sets of calculations explain how to make a 50 µM solution of an RNA oligonucleotide for use in the Silencer™ siRNA Labeling procedure.

Once the ssRNA is in solution, store it at –20°C for up to a few
months, or at –80°C for extended periods of time.

Making a 50 µM Oligonucleotide Solution Based on the nmoles Synthesized

Calculate the amount of nuclease-free water to add as follows:

nmoles synthesized / (0.05 nmoles/µl) = µl for suspension to give a 50 µM solution

Example:
25 nmoles synthesized / (0.05 nmoles/µl) = 500 µl for suspension to give a 50 µM solution

Making a 50 µM Oligonucleotide Solution Based on the Mass Amount of RNA Synthesized

If the specification sheet for the oligonucleotide provides only the mass amount of RNA oligonucleotide synthesized, this is how to calculate the suspension volume necessary to make a 50 µM solution.

Determine the molecular weight of the RNA oligonucleotide:

Calculate the molar amount of RNA synthesized:
The molar amount of RNA synthesized is the mass amount
divided by the molecular weight.

#nmoles synthesized = µg synthesized / 6.7 µg/nmole

Calculate the amount of nuclease-free water needed for suspension:

#nmoles synthesized / (0.05 nmoles/µl) = µl for suspension to give a 50 µM solution

Example:
167.5 µg synthesized / (6.7 µg/nmole) = 25 nmoles synthesized

25 nmoles / (0.05 nmoles/µl) = 500 µl for suspension to give a 50 µM solution

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