Cryostructuring of Polymeric Systems. 55. Retrospective View on the More than 40 Years of Studies Performed in the A.N.Nesmeyanov Institute of Organoelement Compounds with Respect of the Cryostructuring Processes in Polymeric Systems

Abstract

The processes of cryostructuring in polymeric systems, the techniques of the preparation of diverse cryogels and cryostructurates, the physico-chemical mechanisms of their formation, and the applied potential of these advanced polymer materials are all of high scientific and practical interest in many countries. This review article describes and discusses the results of more than 40 years of studies in this field performed by the researchers from the A.N.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences—one of the key centers, where such investigations are carried out. The review includes brief historical information, the description of the main effects and trends characteristic of the cryostructuring processes, the data on the morphological specifics inherent in the polymeric cryogels and cryostructurates, and examples of their implementation for solving certain applied tasks.

Cryostructuring of Polymeric Systems. 57. Spongy Wide-Porous Cryogels Based on the Proteins of Blood Serum: Preparation, Properties and Application as the Carriers of Peptide Bioregulators

“…In general, the microtexture of these spongy cryogels is typical for other known wide-pore chemically cross-linked cryogels formed via the moderate freezing of the solutions (aqueous, as a rule) that contain the relevant precursors [ 11 , 12 , 13 , 14 , 15 , 22 , 32 , 48 , 49 , 51 , 52 , 53 , 54 ]. Dark strand-like structural elements in the images of Figure 3 are the methylene-blue-stained polymeric walls of macropores; the lighter regions of the images are the macropores themselves.…”

“…The key features of these gel matrices are their biocompatibility and, in principle, biodegradability [ 9 , 10 ]. Specific groups of the polypeptide- and protein-composed gels are those prepared in moderately-frozen systems via the so-called cryotropic gelation processes [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ] that result in the formation of proteinaceous cryogels (e.g., see [ 10 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]). Among the latter gel matrices of certain applied interest are biodegradable wide-porous cryogels based on individual blood proteins or their natural (plasma, serum, cell lysate) and artificial mixtures [ 10 , 11 , 22 , 23 , 24 , 25 , 31 , 33 , 34 , 35 , 36 , 37 ].…”

“…(i) by the 3D coupling of the protein macromolecules with the aid of auxiliary cross-linking reagents added to the precursor solution directly prior to its cryogenic processing [ 10 , 11 , 22 , 23 , 24 , 25 , 29 , 30 , 31 , 34 ];…”

“…(ii) by inducing the unfolding of the protein globules with simultaneous interchain cross-linking through the thiol–disulfide exchange reactions, the process also caused by the denaturants introduced into the feed system before its freeze–thaw treatment [ 10 , 22 , 25 , 33 , 36 , 38 ].…”

“…Therefore, such proteinaceous cryogels are non-toxic, upon biodegradation they decompose into harmless natural amino acids, and the wide-pore morphology of these cryogels provides diverse opportunities to load similar sponges with the necessary medicines, i.e., to employ such biopolymeric matrices as drug delivery systems. In particular, cryogels derived from the blood serum albumin have successfully been examined as carriers of antibiotics and bactericides [ 22 , 38 , 39 ] in the respective experiments in vitro and in vivo. In turn, cryogels constructed on the basis of total blood plasma proteins have been applied as covers on full-thickness excision wounds [ 36 ].…”