Soft liquid metal nanoparticles achieve reduced crystal nucleation and ultrarapid rewarming for human bone marrow stromal cell and blood vessel cryopreservation.

High warming rates during cryopreservation are crucial and essential for successful vitrification. However, realizing a faster warming rate in low-concentration cryoprotective agents appears to be challenging for conventional warming process through convective heat transfer. Herein, we developed a liquid metal (LM) nanosystem that can act as a spatial source to significantly enhance the warming rates with near-infrared laser irradiation during the warming process. The synthetic Pluronic F127-liquid metal nanoparticles (PLM NPs) displayed multiple performances with uniform particle size, superior photothermal conversion efficiency (52%), repeatable photothermal stability, and low cytotoxicity. Particularly, it is more difficult for the liquid PLM NPs with less surface free energy to form crystal nucleation than other solid NPs such as gold and Fe3O4, which is beneficial for the cooling process during cryopreservation. The viability of human bone marrow-derived mesenchymal stem cells postcryopreservation reached 78±3%, which is threefold higher than that obtained by the conventional warming method (25±6%). Additionally, the cells postcryopreservation maintained their normal attachment, proliferation, surface marker expression, and intact multilineage differentiation properties. Moreover, the results of mouse tails including blood vessel cryopreservation showed a relatively improved intact structure when using PLM NP rewarming compared with the results of conventional warming. The new LM nanosystem provides a universal platform for cryopreservation that is expected to have potential for widespread applications including bioengineering, cell-based medicine, and clinical translation. STATEMENT OF SIGNIFICANCE: In this study, we fabricated soft liquid metal nanoparticles with high photothermal conversion efficiency, repeatable photothermal stability, and low cytotoxicity. Particularly, soft liquid metal nanoparticles with less surface free energy and suppression effects of ice formation were first introduced to mediate cryopreservation. Superior ice-crystallization inhibition is achieved as a result of less crystal nucleation and ultrarapid rewarming during the freezing and warming processes of cryopreservation, respectively. Collectively, cryopreservation of human bone marrow stromal cells (HBMSCs) and mouse tails including blood vessels can be successfully performed using this new nanoplatform, showing great potential in the application of soft nanoparticles in cryopreservation.

Sperm quality characteristics and fertilization capacity after cryopreservation of rooster semen in extender exposed to a magnetic field.

There has not been as much success in the effectiveness of avian semen cryopreservation as that of mammalian semen cryopreservation. This has been attributed to the unique characteristics of poultry sperm. In the area of mammalian semen, the use of magnetized extenders has enhanced the cryo-resistance of sperm in some species. The applicability of this strategy to avian semen has not yet been evaluated. The purpose of this study was to evaluate the effects on sperm quality and fertility after magnetization of extenders and use of these extenders for cryopreservation of rooster semen. Extenders were passed between two neodymium magnets that produced different magnetic induction values (0, 2000, 4000 and 6000 G). Physicochemical properties of the extenders were assessed and then semen samples were cryopreserved in the magnetized extenders. The smallest cluster sizes and zeta potentials in the extenders were observed in the extender magnetized at 2000 gauss (G). There were greater percentages of sperm total motility, viability and mitochondrial membrane potential in semen treated with the extender magnetized at 2000 G A greater percentage of sperm with enhanced membrane functionality was observed when sperm were stored in extenders magnetized with 2000 G and 4000 G. In a field trial, there were greater percentages of fertility and hatching rates of eggs using semen treated with extenders magnetized at 2000 G and 4000 G. Cryopreservation of rooster semen with magnetized extenders at 2000-4000 G resulted in enhanced quality indices of thawed sperm as well as the fertility capacity of the cryopreserved semen.

[What is the damage gamma-irradiation on solutions-cryoconservants at 77 K?].

Originating under the gamma-radiation action at 77 K on glassy phosphate solutions (6 mol/l) of glycerol and glycero-1-phosphate, H-atoms have motility by virtue of tunneling effect and react with the stabilized radicals of a matrix (OH /H2O+) and with solutes: at storage them in liquid nitrogen the radicals of separation H from carbon atoms C1 and C2 will be derived. According to the assessment maximal radiation "damage" is plotted to the investigated system for year, approximately 1 mol/l.

Antifreeze activities of poly(gamma-glutamic acid) produced by Bacillus licheniformis.

Various enantiomeric isomers, metals salts and molecular sizes of poly(gamma-glutamic acid), gamma-PGA, produced by Bacillus licheniformis CCRC 12826, were prepared and their antifreeze activities were studied by differential scanning calorimetry. The antifreeze activity of gamma-PGA increased as its molecular weight decreased but was indifferent to its D/L-glutamate composition. The antifreeze activity was cation dependent decreasing in the order Mg2+ >> Ca2+ approximately Na+ >> K+ which follows that of inorganic chlorides in that high ionic charge leads to high antifreeze activity. The mechanism by which the cryoprotective effects of gamma-PGA can be explained is still yet to be determined.

Electromagnetic re-warming of cryopreserved tissues: effect of choice of cryoprotectant and sample shape on uniformity of heating.

A method that has been proposed for the cryopreservation of tissues and organs is to add a cryoprotective agent (CPA) in sufficient concentration to allow vitrification, and to use rapid electromagnetic heating to prevent the formation of ice crystals during the re-warming. We have compared the physical and biological properties of four CPAs, measuring the speed and uniformity of heating in a 36 mm sphere placed in a 434 MHz applicator, and the toxicity to ECV304 endothelial cells. Ethanediol and dimethyl sulfoxide were found to be suitable for rapid, uniform heating but toxic to the endothelial cells at vitrifying concentrations. Butane-2,3-diol was less toxic, but the heating patterns were unacceptably non-uniform. Propane-1,2-diol was not significantly more toxic than butane-2,3-diol, and did allow uniform heating. It is therefore the best choice of CPA for the vitrification of tissues. We have shown that the uniformity of heating correlates with the dielectric properties of the perfusate. Furthermore, we have shown that uniform heating is feasible in non-spherical samples provided they are approximately ellipsoidal.