Hello Harmony Borchardt-Wier,

Yes, it is possible. This is due to the inherent properties of DNA, and the conditions present during freezing and storage.

As the primers are frozen, water molecules form ice crystals, which can effectively concentrate the primers and other solutes in the remaining unfrozen solution. This increased local concentration can increase the likelihood of primers encountering each other and forming transient base pairing interactions, even if those interactions are weak.  Also, self-defrosting freezers, can experience temperature fluctuations as they cycle through defrosting periods. During these periods, the shelves and the stored samples can experience transient warming, potentially allowing for brief periods where primers can anneal and form dimers.

If you want to minimize primer dimerization during frozen storage, you should divide your primer stock into smaller aliquots minimizing the number of freeze-thaw cycles.

Store the primers in TE buffer rather than just water. TE buffer helps stabilize the DNA and provides a more suitable pH environment for long-term storage.

Carefully design primer to avoid self-complementarity and cross complementarity which is crucial as it minimizes the potential for dimer formation under suboptimal conditions.

Best,

Thanks! So what I'm hearing (please correct me if I'm wrong), is that it's NOT possible for frozen primers to do this. It's only at the point of thawing and during freezing. So once frozen, they're stable until thawed.

I advise against using an auto defrost freezer for anything lab-related. Not only does it harm reagents, as you point out, but it's murder on frozen tissue samples, since the freeze/thaw cycle will harm the DNA.