Effect of water content on the glass transition temperature of mixtures of sugars, polymers, and penetrating cryoprotectants in physiological buffer

Abstract

Long-term storage of viable mammalian cells is important for applications ranging from in vitro fertilization to cell therapy. Cryopreservation is currently the most common approach, but storage in liquid nitrogen is relatively costly and the requirement for low temperatures during shipping is inconvenient. Desiccation is an alternative strategy with the potential to enable viable cell preservation at more convenient storage temperatures without the need for liquid nitrogen. To achieve stability during storage in the dried state it is necessary to remove enough water that the remaining matrix forms a non-crystalline glassy solid. Thus, the glass transition temperature is a key parameter for design of cell desiccation procedures. In this study, we have investigated the effects of moisture content on the glass transition temperature (Tg) of mixtures of sugars (trehalose or raffinose), polymers (polyvinylpyrrolidone or Ficoll), penetrating cryoprotectants (ethylene glycol, propylene glycol, or dimethyl sulfoxide), and phosphate buffered saline (PBS) solutes. Aqueous solutions were dried to different moisture contents by equilibration with saturated salt solutions, or by baking at 95°C. The glass transition temperatures of the dehydrated samples were then measured by differential scanning calorimetry. As expected, Tg increased with decreasing moisture content. For example, in a desiccation medium containing 0.1 M trehalose in PBS, Tg ranged from about 360 K for a completely dry sample to about 220 K at a water mass fraction of 0.4. Addition of polymers to the solutions increased Tg, while addition of penetrating cryoprotectants decreased Tg. Our results provide insight into the relationship between relative humidity, moisture content and glass transition temperature for cell desiccation solutions containing sugars, polymers and penetrating cryoprotectants.

Polysaccharide-based liquid storage and transport media for non-refrigerated preservation of bacterial pathogens

“…aureus cells. The use of other forms of cysteine as antimicrobials and anti-biofouling materials has been explored previously [19]. While the exact mechanism of inactivation needs to be further investigated, the observation that S .…”

Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material

“…Secondary organic aerosol is a mixture comprising 100 s of components 84,85 . One approach is to group the organic compounds together and then use a binary Gordon-Taylor mixing rule to treat mixtures of water and the lumped organic fraction 86 , which is denoted as the quasi-binary assumption.…”

A Theoretical Study on Trehalose + Water Mixtures for Dry Preservation Purposes

“…Water-THAL mixtures are characterized by the formation of glassy states characterized by the corresponding glass transition temperatures, T g [18]. The formation of glassy structures was inferred from MD simulations by the mixture composition evolution of predicted density (Figure 4a), which evolve through maxima with temperature for each mixture, thus allowing the prediction of T g (Figure 4c).…”