CONICET | Buscador de Institutos y Recursos Humanos

Natural deep eutectic solvents (NADES) are solvents composed of natural metabolites with a deep eutectic behavior, i.e., a significantly lower freezing temperature than those of their components. They consist in combinations of hydrogen bonds donors and acceptors, and show a counterintuitive transformation from solid mixtures to clear, homogeneous liquids upon formation. Their wide solvent capacities, not-toxic properties and biodegradable, not-pollutant and inexpensive components are making NADES popular for a wide variety of applications. The search for new approaches for improving cryopreservation procedures, to confront their current challenges (toxicity and mutagenicity of cryoprotecting agents, low specimen size, high cooling/warming rates), has suggested the employment of NADES for these purposes.As part of a preliminary characterization, the low-temperature behavior of four NADES (composed of β-alanine and either DL-malic acid or citric acid, and choline chloride and ethylene glycol or glycerol) was investigated by differential scanning calorimetry. Alanine-based NADES, in relation to their 3/5 weight water content, show glass transition events between -40 and -80°C. Meanwhile, cholin-based NADES (without water), present no thermal events in the 0° to -80°C range.The effect of increasing water addition causes the apparition of glass transitions in all NADES (at decreasing temperatures, with increasing water content), as well as devitrifications and freezing events.Calcium alginate beads with high sucrose content were used as a crude model for biological systems for cryopreservation. Beads were incubated in NADES, and their low-temperature behavior characterized. Even short incubation times gave rise to behaviors radically different from native beads, evidencing the NADES effect.

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