Chapter 7
Microwave- and Laser-Assisted Drying for the Anhydrous
Preservation of Biologics
Shangping Wang, Susan Trammell, and Gloria D. Elliott
Abstract
Dry preservation has become an attractive approach for the long-term storage of biologics. By removing
water from the matrix to solidify the sample, refrigeration needs are reduced, and thus storage costs are
minimized and shipping logistics greatly simplified. This chapter describes two energy deposition technologies, namely, microwave and laser systems, that have recently been used to enhance the rate and nature of
solution densification for the purpose of anhydrous preservation of feline oocytes, sperm, and egg white
lysozyme in trehalose glass. Several physical screening methodologies used to determine the suitability of an
amorphous matrix for biopreservation are also introduced in this chapter.
Key words Drying technology, Anhydrous preservation, Laser-assisted drying, Microwave drying
1 Introduction
1.1 General
Introduction
The long-term preservation of biologics at supra-zero temperature
is desirable for minimizing the cost and complexity of transportation and storage. This has been commonly achieved by freezedrying, and the biological products that have been preserved by
this approach span proteins, bacteria, sperm, and biological scaffolds [1–4]. However, freeze-drying is a costly and complex technique with a three-step process including (1) freezing, (2) primary
drying (sublimation), and (3) secondary drying (desorption). Many
investigations regarding the preservation of proteins have revealed
that the freeze-drying process itself generates a variety of stresses
that denature proteins. This is especially true of the first freezing
step in the process, which induces low-temperature stress, formation of ice crystals, increased ionic strength, solute concentration
effects, changed pH, and phase separation [5]. These same stresses
can also be very significant when drying cellular materials.
Overcoming hurdles associated with the freezing step and the
mounting osmotic stress during the drying phases remains a significant challenge in achieving a successful dry preserved biologic
Willem F. Wolkers and Harrie ¨ tte Oldenhof (eds.), Cryopreservation and Freeze-Drying Protocols, Methods in Molecular Biology,
vol. 2180, https://doi.org/10.1007/978-1-0716-0783-1_7, © Springer Science+Business Media, LLC, part of Springer Nature 2021
203
Microwave- and Laser-Assisted Drying for the Anhydrous
Preservation of Biologics
Shangping Wang, Susan Trammell, and Gloria D. Elliott
Abstract
Dry preservation has become an attractive approach for the long-term storage of biologics. By removing
water from the matrix to solidify the sample, refrigeration needs are reduced, and thus storage costs are
minimized and shipping logistics greatly simplified. This chapter describes two energy deposition technologies, namely, microwave and laser systems, that have recently been used to enhance the rate and nature of
solution densification for the purpose of anhydrous preservation of feline oocytes, sperm, and egg white
lysozyme in trehalose glass. Several physical screening methodologies used to determine the suitability of an
amorphous matrix for biopreservation are also introduced in this chapter.
Key words Drying technology, Anhydrous preservation, Laser-assisted drying, Microwave drying
1 Introduction
1.1 General
Introduction
The long-term preservation of biologics at supra-zero temperature
is desirable for minimizing the cost and complexity of transportation and storage. This has been commonly achieved by freezedrying, and the biological products that have been preserved by
this approach span proteins, bacteria, sperm, and biological scaffolds [1–4]. However, freeze-drying is a costly and complex technique with a three-step process including (1) freezing, (2) primary
drying (sublimation), and (3) secondary drying (desorption). Many
investigations regarding the preservation of proteins have revealed
that the freeze-drying process itself generates a variety of stresses
that denature proteins. This is especially true of the first freezing
step in the process, which induces low-temperature stress, formation of ice crystals, increased ionic strength, solute concentration
effects, changed pH, and phase separation [5]. These same stresses
can also be very significant when drying cellular materials.
Overcoming hurdles associated with the freezing step and the
mounting osmotic stress during the drying phases remains a significant challenge in achieving a successful dry preserved biologic
Willem F. Wolkers and Harrie ¨ tte Oldenhof (eds.), Cryopreservation and Freeze-Drying Protocols, Methods in Molecular Biology,
vol. 2180, https://doi.org/10.1007/978-1-0716-0783-1_7, © Springer Science+Business Media, LLC, part of Springer Nature 2021
203