A Study of Enthalpic Relaxation of Trehalose-Water Glasses

Trehalose has been shown to be an effective biostabilizer, one explanation for this is that it can easily form glass at near ambient temperatures. Enthalpic relaxation is a physical aging process that occurs in glasses held near, but below, their Tg and is an indicator of the amount of molecular mobility of a particular glass. Since molecular mobility is key to long-term storage biologics in a glassy matrix this study was developed to gain a fundamental understanding of the enthalpic relaxation kinetics of trehalose-water glasses. Through the use of DSC, enthalpic peaks were quantitatively measured for water-trehalose glasses as a function of aging time and aging temperature for three different mass percentages (Mwater/Mtrehalose%, ~0%, ~1.5%, & ~10%). From this data the total amount of relaxation and the relaxation time have been determined using the Cowie-Ferguson equation. Understanding the effects of water on enthalpic relaxation kinetics will help lead to optimized drying protocols and storage parameters.