Cryostructurization of polymeric systems for developing macroporous cryogel as a foundational framework in bioengineering applications

Abstract

Among various fabrication techniques to produce a porous scaffold, thermally-induced phase separation at controlled cryogenic condition leads to the formation of a porous polymeric cryostructure alias cryogel or cryomatrix. Cryostructurization is one of the simple and versatile methods of synthesizing a highly porous and interconnected architecture. The process of cryostructurization is present in comparable fabrication approach of fabricating advanced porous biomaterials with precise control over multiple compositions of precursor units, spatial distributions for accomplishing effective recapitulation of mechanical properties and architectural accuracy at micron-scale with bioactive functionality. The cryogenically-structured polymeric scaffolds are of noteworthy fundamental and applied interest in multidisciplinary areas of science and showed promising matrices in various biotechnological and biomedical areas. The large interconnected pores in cryogels open up a range of applications like the three-dimensional substrate for cell growth, bioreactor for continuous production of scarce molecules, bio-processing and protein purification, an adsorbent for environmental remediation, and biosensor fabrication. Over the past two decades, significant attention to these materials with rigorous expansion in their new designs, and remarkable growth in the number of the publications and patents on cryostructured porous materials has been noticed. This article is covering the progress in cryostructurization technology in the last few decades with principles underlying the mechanism of cryogelation, process optimization, and the recent trend in cryogel for biomedical and bioengineering applications.

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

“…Sixth: Very significant factors that influence substantially the specifics of the macroporous morphology of the polymeric cryogels and cryostructurates are the thermal conditions of all stages of the cryogenic processing. These factors are numerous [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 35 , 38 , 45 , 63 , 66 , 94 , 125 , 144 ], including:…”

“…As at the positive temperatures such solutions transform into very weak gels only after 2–3 months, the freeze–thaw processing yields physical cryogels in several hours and without the use of any cross-linking chemicals [ 220 ]. Of course, the main reason for all similar acceleration effects is the cryoconcentration of the gel-precursors in a small volume of the UFLMP of the respective partially (incompletely) frozen molecular or colloidal solutions [ 5 , 9 , 10 , 16 , 19 , 22 , 27 , 35 , 45 , 63 , 66 , 90 , 112 , 142 ].…”

“…In this case the wide-porous spongy cryogels or cryostructurates are initially fabricated. Further, the sponge-like scaffold is seeded with primary cells, the subsequent propagation of which inside the pore space of the polymeric carrier gives rise to the desired hybrid material filled with the in situ grown biomass [ 5 , 13 , 45 , 59 , 62 , 63 , 64 , 67 , 70 , 71 , 72 , 73 , 77 , 79 , 82 , 94 , 98 ].…”

“…Owing to the combination of similar specific porosity and wide possibility to adjust the physico-chemical characteristics of the various cryogenically structured matrices to the requirements of the goal application, polymeric cryogels and cryostructurates have been extensively examined and used in many practical areas. The following overview publications describe and discuss the generalized data related to the applied potential of similar polymeric materials in such fields as biomaterials (the highest quantity of the respective publications) [ 5 , 12 , 13 , 16 , 17 , 38 , 45 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 ], biotechnology [ 5 , 12 , 13 , 16 , 17 , 18 , 19 , 30 , …”

“…In the last decades, the application of the cryostructuring processes for the preparation of materials based on natural or synthetic polymers featuring a desired set of properties, the study of such materials and their use are the subjects of scientific and applied activities in many countries [ 26 ]. The references to the above-indicated publications [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , ...…”