Freeze drying (lyophilization) is an established method for long-term storage, of biomolecules. The general process is used to preserve bacteria, fungi, yeasts, proteins, nucleic acids, and any other molecules which may degrade in the presence of water.
The approaches vary widely, but they all follow the standard process of:
- Freezing of the sample
- Applying of a high vacuum (<200 mTorrs)
- Warming of the sample under vacuum causing water sublimation
- Drying the sample further by warming to almost ambient temperature and driving off residual water
- Sealing of sample to prevent future water uptake
Four significant considerations for freeze drying:
- First consideration, culturing and preparing the samples.
- Second consideration, suspending the sample in the correct freeze drying medium with a lyoprotectant and exicipents.
- Third consideration, choosing the optimal vials for the sample as well as the machine.
- Fourth considersation, storing vials in refrigeration.