Lyophilization: Freeze Drying

Complex and expensive method of drying material, usually reserved for delicate heat sensitive materialsTerm derived from Greek “made solvent-loving”

Principle:- Sublimation = conversion of water from frozen/solid to gas/vapour without

going through a liquid state (removes moisture while specimens remain frozen)

- Extracts water- creates a dry porous material- can be stored without refrigeration- mammalian cells are destroyed by lyophilization- materials are easily rehydrated with water

Benefit: avoid protein denaturation and undesirable shrinkage

Alternative: liquid phase drying

Process:1. Place wet sample in vacuum chamber and sample is frozen by evaporative

cooling (can centrifuge to help dry faster and minimize frothing)2. Alternatively can freeze before placing under vacuum