Abstract
A promising direction for long-term storage of cells at relatively high temperatures may be their encapsulation with nanoscale biologically inert materials capable of creating a shell around microdroplets of a cell suspension, which, on the one hand, provides the possibility of gas exchange between the suspension and the external environment, and on the other hand, inhibits the processes of cell life, so transferring them to a state close to suspended animation. The method of low-temperature 1H NMR spectroscopy was used to study the process of hydration of lactobacilli, the effect of a weakly polar organic medium on it and the encapsulation of cells with silica. The aim of this work was to study the hydration of cell suspensions and the viability of lactic acid bacteria cells encapsulated with silica and the penetration possibility of such an active substance as trifluoroacetic acid into them. As a result of the studies carried out, it has been shown that the spectral parameters of water in concentrated cell suspensions of lactic acid bacteria strongly depend on the concentration of the suspension, which is probably associated with the possibility of the formation of a stable cell gel, which can be encapsulated by silica particles without its destruction in both air and a chloroform medium with addition of trifluoroacetic acid. The radial distribution curves of non-freezing water clusters have two maxima corresponding to R = 2 and 20–100 nm. The contribution to the distribution of the second maximum increases with increasing water concentration.
Highlights
For long-term storage of cell suspensions, the method of freezing them with a cryoprotectant at the temperature of –196 °C is widely used [1, 2]
The aim of this work was to study the hydration of cell suspensions and the viability of lactic acid bacteria cells encapsulated with silica and the penetration possibility of such an active substance as trifluoroacetic acid (TFAA) through the hydrophilic barrier into cells
It has been shown that the spectral parameters of water in concentrated cell suspensions of lactic acid bacteria strongly depend on the concentration of the suspension, which is probably associated with the possibility of the formation of a stable cell gel, which can be encapsulated by TS-100 silica particles in both air and chloroform medium with the addition of trifluoroacetic acid
Summary
For long-term storage of cell suspensions, the method of freezing them with a cryoprotectant (glycerol or DMSO) at the temperature of –196 °C (liquid dinitrogen) is widely used [1, 2]. Most of the intracellular water is removed from the cells This is due to the fact that at temperatures down to –30 °С such transmembrane transfer of intracellular water can occur, which is practically not accompanied by the formation of intracellular ice. This is due to the fact that at temperatures down to –30 °С such transmembrane transfer of intracellular water can occur, which is practically not accompanied by the formation of intracellular ice At this stage, the cooling rate is limited by the possibility of transmembrane diffusion (different for different types of cells). The cooling rate is limited by the possibility of transmembrane diffusion (different for different types of cells) This is followed by the deep freezing stage, which leads to damage to frozen cells [6]
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