We present herein an experimental study on the ice-nucleation kinetics of two recently introduced aqueous supercooling modalities—oil-sealed isobaric supercooling and isochoric supercooling. A series of constant-cooling rate experiments compare the apparent nucleation temperatures of pure water supercooled under these modalities with conventional open-air isobaric supercooling, demonstrating that both methods significantly enhance the supercoolability of the system as compared to open-air supercooling. However, while the mean nucleation temperatures of the two methods are statistically comparable, isochoric supercooling displays approximately half the variability of isobaric oil-sealed supercooling, which may have important implications on the design of supercooling-based biopreservation protocols in which stability and reproducibility are paramount.

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This technical paper introduces a novel organ preservation system based on isochoric (constant volume) supercooling. The system is designed to enhance the stability of the metastable supercooling state, offering potential long-term preservation of large biological organs at subfreezing temperatures without the need for cryoprotectant additives. Detailed technical designs and usage protocols are provided for researchers interested in exploring this field. The paper also presents a control system based on the thermodynamics of isochoric freezing, utilizing pressure monitoring for process control. Sham experiments were performed using whole pig liver sourced from a local food supplier to evaluate the system’s ability to sustain supercooling without ice nucleation for extended periods. The results demonstrated sustained supercooling without ice nucleation in pig liver tissue for 24 and 48 h. These findings suggest the potential of this technology for large-volume, cryoprotectant-free organ preservation with real-time control over the preservation process. The simplicity of the isochoric supercooling device and the design details provided in the paper are expected to serve as encouragement for other researchers in the field to pursue further research on isochoric supercooling. However, final evidence that these preserved organs can be successfully transplanted is still lacking.

Freezing liquids into ice is a complex simulation and is called a phase transformation or phase change. Isochoric (constant volume) preservation is a new thermodynamic concept that takes advantage of an until now ignored aspect of thermodynamics, life under conditions of constant volume as opposed to the conventionally studied life conditions of constant pressure. Isochoric system are simple constant volume devices, made of steel, capable of withstanding the pressures that develop in the system, with minimal deformation. Because ice-I is less dense than water, the formation of an ice nucleus in an isochoric (constant volume) chamber will cause an increase in pressure. Traditionally, ice formation is performed in an isobaric process (constant pressure) at 1 atm, because this is our natural environment and it is most convenient experimentally. The goal of this study is to introduce the fundamental thermodynamic principles and boundary conditions of isochoric (constant volume) simulations at low temperatures. In this analysis we intend to shows that homogeneous ice nucleation can be thermodynamically improbable in an isochoric system.

There is a developing enthusiasm for discovering new methods, cryoprotectants, systems and devices for cells, tissues, and organ preservation in medicine, in sub-zero temperature conditions and a growing interest in developing more efficient and economical methods for long-term preservation of food in a frozen state. Most of the preservation protocols currently used in medicine and food preservation involve the use of atmospheric pressure, and temperatures lower than normal body temperature in medicine, or lower than room temperature in the food industry. In this state of the art review, we analyzed the results of a new preservation method that uses an isochoric system. We aimed to offer a clear overview of the potential of this new technology. Firstly, to study the origins of isochoric preservation, we searched using the WoS Database. A search with the world "isochoric" returned 488 results. A more specific search of the term "isochoric freezing" returned 94 results. From these searches, we selected the 12 most relevant articles and discuss them here in detail. We present an overall characterization and criticism of the current use and potential of this new preservation method that can be used in the medicine and food industry. The main findings indicate encouraging results for the tested biological matter, including for the preservation of food products (e.g.cherries, spinach, potatoes), biological organisms (e. g. Caenorhabditis elegans, Escherichia coli, Listeria, Salmonella typhimurium), organs (e.g. rat hearts), tissues (e. g., tilapia fish filets) or cells (e. g., mammalian cells, pancreatic cells). Accordingly, we conclude that the isochoric system holds huge potential as a new technique in the field of preservation.