I have a PVDF membrane with the proteins blotted onto it. I placed the membrane in blocking solution (2.5% non fat milk) overnight but I don't have the right antibody to probe it with. Can I just store the membrane as such (i.e. dry it at this point and store at -20oC) until I get the right antibody to probe it with or should I strip it of the blocking solution before storage?
Once the protein is on the membrane you should not freeze PVDF, you can leave the membrane at 4c in PBS/ TBS/ PBST or TBST and it should be fine for a month or so if you dry it after it has been in MILK or PBS it will form salt crystals so do not dry it out, there are ways to dry membranes and store them at room temp. Also it is best to block in 5% nonfat milk and then leave some milk 1% or 2% with the primary antibody..
Once you wash the PVDF membrane extensively to get rid of salts you should even be able to store it after room temperature drying and re-wet it once you have the antibody. Once dry you should be able to store it long term at room temperature, just wrap it in aluminium foil. We had good experience with that if we needed long term storage of PVDF membranes.
PVDF is a very durable membrane - you're right to use 2.5% NFDM, any higher can block your antigenic sites. Generally it is not recommended to store primary antibodies in NFDM as after all milk is protein. With storing your membranes, I would remove the blocking (this is what can go off and cause fungal growth for long term storage). Then dry your membrane. Once you dry PVDF after you have transferred your protein is "fixed" - I had many a blot that I re-used (stripping and reprobing) that offered the same publication quality blots over the course of a few years. When you store it, keep it as Daniel suggested in Aluminium foil (or cling film). When you come to reuse it, just wet it with PBST (Methanol makes the PVDF hydrophillic - which is what you want for transfer). PVDF is a great membrane and very versatile so it will be good until you use/find your antibodies.
Meena - quick clarification - so when you rewet the membrane after long term usage do you dip it in methanol or PBST?
You can store your PVDF-strips best after blocking under dry conditions. It can be at 4 °C or even frozen. For commercial western / line blots some sugar is added to the blocking solution. Mostly 1 - 2% Glucose + 1 - 2 % Mannose is used here. This will help to bind some residual water near to the proteins to prevent any denaturation. Remove the blocking buffer by washing with water, containing the both sugars. Let the strips dry and store them between some filter paper or in a tube.
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