Xeroprotective

Xeroprotective is an adjective used to describe substances, strategies, or responses that guard biological material against desiccation, the state of extreme dryness. In biology, xeroprotectants are small molecules, polymers, or proteins that stabilize cellular components during drying and facilitate long-term storage in a desiccated state. The term is used in fields such as microbiology, plant science, and biopreservation.

Mechanisms of xeroprotection include replacement of water by hydrogen-bonding partners (the water replacement hypothesis), the formation of a glassy or vitrified matrix that immobilizes biomolecules, and stabilization of membranes and proteins through osmotic effects or excluded-volume interactions. Common xeroprotectants include disaccharides such as trehalose and sucrose, sugar alcohols like glycerol, and amino acid derivatives such as proline and glycine betaine. Some organisms naturally accumulate xeroprotectants to endure drought, including desiccation-tolerant seeds, tardigrades, and certain nematodes. In industry, xeroprotectants enable desiccation-based preservation of enzymes, vaccines, probiotics, and other biomaterials, as well as the dried storage of seeds and biobanked samples.

Xeroprotection differs from cryoprotection, which aims to prevent damage from freezing rather than drying. Ongoing research seeks to optimize protective formulations, understand desiccation tolerance across taxa, and expand dried-storage technologies, while addressing challenges such as drying rate sensitivity and potential toxicity at high concentrations.