Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures

Area of Science:

• Cryobiology
• Biophysics
• Materials Science

Background:

• Cryopreservation is vital for tissue engineering and organ transplantation.
• Isochoric (constant volume) systems are being explored for cryopreservation.
• Previous studies measured pressure-temperature relations from 0°C to -20°C.

Purpose of the Study:

• To extend pressure-temperature measurements in aqueous isochoric systems to liquid nitrogen temperatures.
• To investigate the behavior of pure water and Me2SO solutions under isochoric conditions at sub-zero temperatures.

Main Methods:

• Developed a novel isochoric device capable of withstanding temperatures down to liquid nitrogen and pressures up to 413 MPa.
• Utilized a real-time pressure transducer to monitor pressure within the isochoric chamber.
• Conducted measurements on pure water and various concentrations of Me2SO solutions, ensuring removal of undissolved gases.

Main Results:

• Presented temperature-pressure data for pure water and solutions from -5°C to liquid nitrogen temperatures.
• Observed a surprising increase in pressure below the triple point (-21.993°C, 209.9 MPa) persisting to liquid nitrogen temperatures.
• Found no pressure increase during rapid cooling to liquid nitrogen temperatures for Me2SO concentrations predicted to vitrify, but ice formation induced pressure increases.

Conclusions:

• The obtained data are crucial for designing effective isochoric cryopreservation protocols.
• Pressure monitoring in constant volume systems provides insights into vitrification and devitrification processes.
• This research enhances understanding of cryopreservation dynamics in aqueous solutions.