Question:

What are the best practices for the long-term storage of oligonucleotides to ensure their stability?

Answer:

Most oligonucleotides remain stable for over a year when stored dry at 4°C. However, for periods extending beyond a year, it’s recommended to store them at -20°C. This temperature is optimal for maintaining oligonucleotide integrity, whether they are in a solution or dry form.

Use of Nuclease-Free Medium

When not stored dry, oligonucleotides should be in a DNase and RNase-free medium, such as TE buffer or water, to prevent degradation.

Minimizing Exposure to UV Light

Fluorescently-labeled oligonucleotides are particularly sensitive to light, which can cause photobleaching. Therefore, these should be stored in the dark to preserve their fluorescent properties.

Avoiding Repeated Freeze-Thaw Cycles

Frequent changes in temperature can degrade oligonucleotides. It’s best to aliquot them into smaller volumes to avoid repeated freeze-thaw cycles.

RNA Oligonucleotides

RNA oligonucleotides are less stable than DNA due to their chemical structure. For long-term storage, they should be kept as an ethanol precipitate at -80°C for greater stability.

By following these guidelines, researchers can maintain the integrity of their oligonucleotides, ensuring that they are reliable for future experiments and applications.