Oligonucleotides as Inhibitors of Ice Recrystallization

Abstract

Oligonucleotides of adenine (A20), guanine (G20), cytosine (C20), thymine (T20), cytosine–guanine ((CG)20), and adenine–thymine ((AT)20) were investigated as model compounds for ice recrystallization inhibition (IRI). Dehydroxy uracil (dU20), U20, and T20 were also compared to investigate the effect of minute changes in the hydrophobicity of the oligonucleotides on the IRI activity. Among the oligonucleotides considered in this study, T20 exhibited the best performance for IRI. In addition, the degree of polymerization of oligothymines varied over 5, 10, 20, 30, 50, and 100, and T20 was found to be the most effective for IRI. The IRI mechanism was investigated by comparing U20 and T20, which exhibited the lowest and highest IRI activity, respectively, among the oligonucleotides for their dynamic ice-shaping, thermal hysteresis, and ice nucleation inhibition. Little or no dynamic ice-shaping activity and small thermal hysteresis were observed for both nucleotides. All of the findings suggest that not the ice–polymer adhesion but the hydrophobic interactions of T20 in the interface layer might interfere with the water deposition on the ice crystal surfaces and contribute to the IRI activity of the T20 oligonucleotide.

Poly(l-alanine-co-l-threonine succinate) as a Biomimetic Cryoprotectant

“…When PATs-2 and PATs-4 were compared, which have a similar the degree of succinylation but differ in l -Ala content, β-sheet content, IRI, INI, and TH activities increased as the L- Ala content increased. In particular, PATs-3 and PATs-4 with a high l -Ala content exhibited moderately high IRI activity with 30–35% of MLGS to that of PBS, which is similar to that of oligothymine (T20), facially amphiphilic copolymers of poly­(fulvo- co -oxo), nylon-3 copolymers. − High DIS activities of PATs-2, PATs-3, and PATs-4 suggest that succinate groups as well as the l -Ala content play a role in the binding of PATs to the ice crystal surface. In particular, the LDH stabilization activity during freeze–thaw cycles was excellent for PATs-2, PATs-3, and PATs-4.…”

“…Both PATs-3 and PATs-4 showing rather high IRI activity have a similar 68–69% of l -Ala content. The control of hydrophobicity must be an important factor in designing a polymer with a high IRI activity as reported in PEG–poly­( l -Ala) block copolymers, oligothymines, and facially amphiphilic copolymers. ,, Based on the MLGS analysis, PATs-3 and PATs-4 have moderately high IRI activity compared to oligothymine (T20), facially amphiphilic copolymers of poly­(fulvo- co -oxo), nylon-3 copolymers with the 50:50 composition of a dimethyl methylammonium/monohydroxy methyl group. − Molecular weight affects the IRI activity. ,,, The IRI activity of PVA is low for polymers with molecular weights less than 2 kDa.…”

Essential Role of Methyl Groups in Ice Recrystallization Inhibition of Antifreeze Silver Nanoparticles Studied by Surface-Enhanced Raman Scattering

“…Some dynamic ice-shaping studies showed that methyl-mediated IRI materials do not bind to the ice surfaces. , Therefore, unlike antifreeze materials having OH groups, MeMP-AgNP and MeOMP-AgNP do not interact with any facets of ice crystals through hydrogen bonding. It has been indicated that the Raman band of methyl groups shows a blue shift when they interact directly with water through hydrogen bonds. , However, as discussed above, upon freezing, the Raman band of methyl groups showed red shifts in some cases and blue shifts in others.…”

“…Freezing is commonly used in biopharmaceutical manufacturing and the storage of foods, tissues, and cells, but ice recrystallization can damage these substances during cryopreservation. − Ice recrystallization causes mechanical damage and osmotic shock, which can decrease cell recovery, reduce cell viability, and impair cell function. During the recrystallization process, larger ice crystals grow at the expense of smaller ones, known as Ostwald ripening.…”

The Valence-Dependent Activity of Colloidal Molecules as Ice Recrystallization Inhibitors

“…The scaled-up production of AFPs with a reasonable cost is still difficult. Synthetic polymers have been widely developed as AFP biomimetics, such as poly(vinyl alcohol) (PVA), − poly(ethylene glycol) (PEG), and their block copolymers. , Besides, pronounced IRI activities have also been seen on graphene oxide (GO), nanocelluloses with amphiphilic structures, and facially amphipathic glycopolymers synthesized by ring-opening metathesis polymerization, analogous to natural antifreezing glycoprotein such as poly([( l -Ala) x - co -( l -Thr succinate) y , nanogels, high molecular weight polyproline, oligonucleotides, and surface-functionalized MOF particles . Since synthetic materials are less active than natural AFPs, researchers are turning their focus to the higher-ordered nanostructures .…”