Liquid nitrogen (L.N.): liquid density at the triple point is 0.807 g/ml. is inert, colorless, odorless, non-corrosive, nonflammable and extremely cold.
Liquid nitrogen boils at -196°C and Is a cryogenic fluid which is potentially capable of causing rapid frostbite on contact with living tissue.
Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as (typically) 77°K or -196°C (the boiling point of liquid nitrogen)
When cryoprotectant solutions are not used, the cells being preserved are often damaged due to freezing during the approach to low temperatures or warming to room temperature.
A cryoprotectant is a substance that is used to protect biological tissue from freezing damage (damage due to ice formation),
Cryoprolectants act like antifreeze: they lower the freezing temperature. They also increase the viscosity. Instead of crystallizing, the syrupy solution turns into an amorphous ice.
