Determination of the relaxation characteristics of sugar glasses embedded in microfiber substrates

Abstract

Recently there has been considerable interest in developing sugar glasses that enable storage of biologics without refrigeration. Microfiber filter papers are good substrates for drying biologics in the presence of sugar glass-formers, providing for an even distribution of samples and an enhanced surface area for drying, but the opaqueness prevents macroscopic observation of the sample and can introduce complexities that impede physical characterization. Because drying kinetics and processing conditions can impact the relaxation dynamics (e.g., α- and β-relaxation), which can influence the efficacy of the glass as a stabilizer, methods are needed that can enable a determination of relaxation phenomena of sugar glasses in such complex environments. In this study we present a method which provides verification of the absence of crystallinity following drying on glass fiber filter paper and also enables the determination of relaxation characteristics of amorphous sugar compositions embedded within these filter substrates. Using material pockets to contain the sugar glass-embedded microfiber paper, the α-relaxation temperature, Tα, was determined as a function of the water content in trehalose and sucrose samples using Dynamic Mechanical Analysis (DMA). Results were verified by comparison with previous calorimetric and spectroscopic studies. The data also demonstrated the plasticizing effects of water, as Tα was shown to correlate with water content via a Gordon-Taylor-like relationship. Our findings validate a new approach for determining the relaxation characteristics of microfiber embedded sugar glasses, and offer new insights into the relaxation characteristics of glasses prepared by microwave-assisted drying on filter papers.

Effects of Water on Structure and Dynamics of Trehalose Glasses at Low Water Contents and its Relationship to Preservation Outcomes

“…Solidification of cells in an adherent state can induce significant mechanical stress to cells during processing and is generally avoided. Microwave-assisted drying is recognized as a fast, uniform and reproducible method to dehydrate biomaterials into the glassy state 20 21 , and it has been successfully applied to dry preserve cat germinal vesicles 17 . Representative micrographs showing the distribution of total cells, stained with Hoechst 33342 and membrane compromised cells, stained with Sytox Green, are shown in Fig.…”

Local Minimum in Fragility for Trehalose/Glycerol Mixtures: Implications for Biopharmaceutical Stabilization

“…A DMA (Q800, TA Instruments, New Castle, DE) was utilized to conduct temperature step/frequency sweep experiments on amorphous samples. A sample of the lyophilized trehalose/glycerol mixtures (10–20 mg) was loaded into a stainless steel material pocket (PerkinElmer, Norwalk, CT) and melted on a heating plate at 480 K to remove the last trace of moisture in the lyophilized mixtures. The anhydrous glassy state was obtained by quenching the melt on a cold steel surface (∼283 K) cooled by liquid nitrogen, and then the sample was immediately subjected to the temperature step/frequency sweep experiment.…”