Isothermal Desiccation and Vitrification Kinetics of Trehalose−Dextran Solutions

Abstract

The promise of dried state preservation is based on the hypothesis that lowering molecular mobility to halt chemical reaction and deterioration rates is the primary factor for the long-term stability of the dried specimen. In this research, the feasibility of utilizing isothermal, isobaric vitrification as an economical alternative to the preservation technologies currently in use (mainly, cryopreservation and lyophilization) is explored. Desiccation and vitrification kinetics of model trehalose and trehalose-dextran systems were examined using gravimetric analysis, modulated differential scanning calorimetry, and X-ray crystallography. It was shown that vitrification can be achieved isothermally without crystallization and that vitrification of trehalose solutions can be significantly accelerated by incorporating high-molecular-weight dextrans. Additionally, it was shown that, for the same water content, the glass transition temperature of the trehalose-dextran solution is significantly higher than that of the binary trehalose solution, making the glassy state achievable and storage feasible.

A Spin-Drying Technique for Lyopreservation of Mammalian Cells

“…Mammalian cells are highly sensitive to hyperosmotic stress, and this characteristic has been an impediment to develop a successful dry preservation technique. 5,28 Even with the protection from intracellular trehalose, cell samples fail to survive desiccation stress when desiccated with conventional slow drying techniques. 2 Recent studies indicated that the slow rate of drying in conventional techniques may be a reason for the failure, 5,41,48 and to develop a successful processing technique for lyopreservation, it is important to minimize the exposure time of the cells to the deleterious effects of supersaturated solutions.…”

“…5,28 Even with the protection from intracellular trehalose, cell samples fail to survive desiccation stress when desiccated with conventional slow drying techniques. 2 Recent studies indicated that the slow rate of drying in conventional techniques may be a reason for the failure, 5,41,48 and to develop a successful processing technique for lyopreservation, it is important to minimize the exposure time of the cells to the deleterious effects of supersaturated solutions. 5,28 For this reason, researchers have looked at developing several fast desiccation techniques for dry processing of cells including vacuum drying, 9 microwave drying, 16 and nebulization.…”

“…5 Commonly, cell samples are suspended in droplets of solution containing trehalose and then dried passively in air of low relative humidity. 2,40,44 Physicochemical studies showed that these sugar solutions exhibit a variety of complex phenomena during drying such as skin formation, cracking, and variable water loss kinetics.…”

“…2,40,44 Physicochemical studies showed that these sugar solutions exhibit a variety of complex phenomena during drying such as skin formation, cracking, and variable water loss kinetics. 5 Such events lead to prolonged hyperosmotic stress and local non-uniformities in the dried sample which in turn potentially promote ''poor'' outcomes following rehydration. 3,5 Spin drying helps overcome the above problems.…”

“…5 Such events lead to prolonged hyperosmotic stress and local non-uniformities in the dried sample which in turn potentially promote ''poor'' outcomes following rehydration. 3,5 Spin drying helps overcome the above problems. The thin layer of solution achieved during spin drying promotes rapid evaporation of water from the sample.…”