Our lab has a frozen stock solution of polyinosinic:polycytidylic acid (poly IC). It's been in our -20C freezer since 2004. We've used it on and off since then. The concentration is 2.5mg/mL
I recently defrosted it for a cell culture. But once it became a solution, I saw a transparent mass in the Eppendorf. It looks like a small piece of plastic wrap/Ziploc bag. I tried to disperse it using a P1000 pipette, but the clump would not dissolve
I looked at the literature, and no paper mentions a precipitate.
Does anyone know if this clump is normal? Or should I get a new source of poly IC?
Thanks very much.
Without knowing the concentration of stored poly I:C solution, it is difficult to guess what might have contributed to "clump" formation in tubes with the poly I:C solution. It is likely that during the storage of the solution for years, water in the tube evaporated, resulting in insoluble pol I:C polymer. Adding sterile PBS or TE and warming the tube could redissolve the "clump".
Dr. Divaker Choubey- thank you for your input. The concentration was 2.5mg/mL.
Would warming the tube cause conformational changes in the poly IC? I was hesitant to try that.
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