Moisture sorption characteristics and thermophysical properties of trehalose-PBS mixtures.

The goal of the study was to quantify the thermophysical properties and the moisture sorption characteristics of the trehalose-PBS (phosphate-buffered saline) from the desiccation preservation perspective. A moisture sorption study was undertaken to determine the desorption isotherms of the trehalose-PBS mixtures. The Brunauer, Emmett, and Teller (BET)-equation and the Guggenheim, Anderson, and de Boer equation were used to quantify the desorption data. The glass transition temperature of the mixtures of trehalose-PBS, equilibrated at different relative humidities was studied using a differential scanning calorimeter. Fourier transform infrared spectroscopy was used to study the molecular interaction between the trehalose and PBS mixtures. The results showed that the addition of PBS to the trehalose mixture causes a shift from the type II isotherm to a type III isotherm (characterized by BET equation) which may have detrimental effect on cell desiccation. The results showed that an increase in PBS mass fraction in the trehalose-PBS mixture causes a decrease in the glass transition temperature (Tg) of the mixture and also a decrease in the hydrogen bonding capacity of the trehalose glasses. The addition of PBS to trehalose posed some challenges and should be subject to further optimization to use it in desiccation preservation of biologics.