Image courtesy of Thermo Fisher Scientific
Problem: While ultra-low temperature freezers serve many critical purposes in the lab, sample preparation should not be one of them. Yet labs across a variety of disciplines continue to use ultralow temperature freezers to prepare samples prior to cold storage or to cool warmer samples despite lacking the speed or refrigeration capacity needed to rapidly freeze samples prior to cold storage. As such, using an ultra-low temperature freezer to prepare samples puts significant strain on the freezer, ultimately shortening the life span of the unit while impacting sample integrity and viability.
Solution: To best prepare samples for long-term storage at ultra-low temperatures, researchers need to rapidly freeze them in order to preserve cellular structures and ensure viability of the samples once thawed again. Performing this rapid freeze in a blast freezer not only ensures the rapid freezing of samples but also reduces the stress placed on a sample storage freezer, while enabling quick and efficient freezing.
Blast freezing is accomplished by using a specially designed freezer that rapidly cools samples in preparation for long-term storage. By quickly and effectively removing the heat from a sample, researchers can minimize the formation of ice crystals that can negatively impact the viability of cell membranes. Blast freezers can be used for medical applications as a means to rapidly freeze plasma as well as for general-purpose and bioprocessing applications since they can accommodate staggering loads and a variety of vessels including 10 liter carboys, bottles, racks with vials, and more.
One such example is the Thermo Scientific™ XBF40 series of -40°C blast freezers which contains three individual compartments that allow users to rapidly freeze samples without jeopardizing the freeze profile of products already in the blast freezer. The versatile design also offers forcedair circulation for accelerated airflow for rapid freezing and a self-contained refrigeration system for application flexibility and increased ease-of-use. With its plug and play design, this freezer fits into the lab without the need for custom installation or remote compressor systems.
In an internal test comparing freezing times between the Thermo Scientific XBF40D -40°C blast freezer and a standard Thermo Scientific 600 box capacity -80°C ultralow temperature freezer, 24 5 L bottles filled with 3.5L of tap water were placed in each and, on average, the water reached -70°C 75 percent faster by using the XBF blast freezer first to reach -38°C, then transferring to the ultralow freezer. Another study, which looked at the efficiency of blast freezers, compared the storage of 5 L bottles filled with 3.5 L of tap water at a starting temperature of around 22°C. The tap water reached 0°C in an average of 100 minutes and -30°C in an average of 600 minutes. A grouping of 2mL vials at a starting temperature of around 20°C reached 0°C in five minutes and -30°C in 25 minutes. These examples help to demonstrate how much time one can save when using a blast freezer such as the XBF40D to bring critical samples, or volumes, to storage temperatures.
Now, labs no longer need to be concerned with the strain cold storage sample preparation and rapid plasma freezing can place on critical freezing equipment. Blast freezers such as the Thermo Scientific XBF40 series offer a versatile design, with the capability of preparing a variety of sample types for long term cold storage, while preserving cellular functionality and viability.
For more information, please visit www.thermoscientific.com/cold
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