A Review of the Material Characteristics, Antifreeze Mechanisms, and Applications of Cryoprotectants (CPAs)

Table 1

Structure, mechanism, and applications of typical CPAs.

Types of CPA		Structure	Mechanism	Application
Impermeable CPAs	AFP^a		Strong, irreversible binding to ice surfaces and causing the ice surface to bend, lowering the freezing point and inhibiting ice recrystallization	Food, agriculture, cryomedicine
	PVA		Week, reversible adsorption with ice surface, and it can inhibit ice recrystallization, generally cannot lower freezing point	Couse with other CPAs
	Polyampholytes^b		Protecting cell membranes	A variety of cells
	GO		Binding to ice in the form of hydrogen bond and inhibits ice recrystallization	Sperm cells
Permeable CPAs	DMSO		Diffusing through membranes, reducing dehydration of cells during freezing	A variety of cells (standard CPA)
	Proline		Diffusing through membranes, reducing dehydration, breaking hydrogen bonds between ice crystals, reducing the formation of large ice crystals	A variety of cells, and living organisms such as fruit flies and ants

^aThe simple schematic of snow flea antifreeze protein structure [10]. ^bThe structure refers to COOH-PLL [19].