Most modified oligos can be stored and resuspended just as unmodified oligos. For long term storage, temperature is the most important factor to consider. For long term storage, whether oligos are dried down, or resuspended in water (non-DEPC treated) or TE Buffer (10 mM Tris pH 8.0, 0.1 mM EDTA; such as IDTE), it is optimal to store them frozen at -20°C. For room temperature or 4°C storage, oligos that are resuspended in TE buffer are more stable than dry oligos. Oligos that are stored in water are the least stable. However, at 4°C oligos stored under all of these conditions are stable for at least 60 weeks.
It is ideal to store oligos in the dark. Exposure to UV light should be avoided, and ambient lab light should be minimized, particularly for some types of modified oligos.
Please see the Technical Report, Oligonucleotide Stability Study, for data on oligonucleotide storage and a more thorough explanation.
For resuspension, we recommend making a stock solution and then smaller working aliquots to avoid contamination of the entire stock, and to limit repeated freeze/thaw cycles that can lead to degradation of the oligo.
Notes for specific modifications:
Oligos containing photocleavable or photolabile modifications such as Bromo-dU, PC Spacer, PC Biotin, and PC Linker, should be kept away from light and are therefore shipped in amber tubes. We recommend storing them in dark tubes or wrap them in foil.
Also, amine-modified oligos that will be used in NHS ester reactions should not be hydrated in buffers containing amines (such as TRIS), as the amines in the buffer will compete with the amine-modified oligo in the reaction. These amine-modified oligos can instead be resuspended in 0.1 mM EDTA or non-DEPC treated, nuclease-free water and stored at -20°C.