The diversity and safety of nanofibrillated cellulose (NFC) hydrogels have gained a vast amount of interest at the pharmaceutical site in recent years. Moreover, this biomaterial has a high potential to be utilized as a protective matrix during the freeze-drying of heat-sensitive pharmaceuticals and biologics to increase their properties for long-term storing at room temperature and transportation. Since freeze-drying and subsequent reconstitution have not been optimized for this biomaterial, we must find a wider understanding of the process itself as well as the molecular level interactions between the NFC hydrogel and the most suitable lyoprotectants. Herein we optimized the reconstitution of the freeze-dried NFC hydrogel by considering critical quality attributes required to ensure the success of the process and gained insights of the obtained experimental data by simulating the effects of the used lyoprotectants on water and NFC. We discovered the correlation between the measured characteristics and molecular dynamics simulations and obtained successful freeze-drying and subsequent reconstitution of NFC hydrogel with the presence of 300 mM of sucrose. These findings demonstrated the possibility of using the simulations together with the experimental measurements to obtain a more comprehensive way to design a successful freeze-drying process, which could be utilized in future pharmaceutical applications.
Keywords: freeze-drying; molecular dynamics simulations; nanofibrillated cellulose hydrogel; ptychographic X-ray computed tomography; residual water content; rheology; sucrose; trehalose.