Cryogels

It was reported that PEGylated lipase entrapped in PVA cryogel could be conveniently used in organic solvent biocatalysis [279], This method for enzyme immobilization is more convenient in comparison to other types of immobilization that take advantage of enzyme covalent linkage to insoluble matrix, since the chemical step which is time consuming and harmful to enzyme activity is avoided. The application of this catalytic system to the hydrolysis of acetoxycoumarins demonstrated the feasibility of proposed method in the hydrolysis products of pharmaceutical interest and to obtain regioselective enrichment of one of the two monodeacetylated derivatives. 

Physical crosslinked PVA cryogel is considered to have a good permeability for oxygen that is a desirable property for biomaterials [1]. 

L. Doretti, D. Ferrara, S. Lora, F. Schiavon and F.M. Veronese, Acetylcholine biosensor involving entrapment of acetylcholinesterase and poly (ethylene glycol)-modified choline oxidase in a poly(vinyl alcohol) cryogel membrane, Enzyme Microb. Technol., 27 (2000) 279-285. 

Kumar A, Bansal V, Andersson J, Roychoudhury PK, Mattiasson B (2006), Super-macroporous cryogel matrix for integrated protein isolation - immobilized metal affinity chromatographic purification of urokinase from cell culture broth of a human kidney cell line, J. Chromatogr. A 1103 35-42. 

Both composite gels and cryogels thus obtained were capable of heat-induced collapse at certain critical temperatures. It was found that the extent of the collapse of the composite gel prepared at room temperature was much smaller and without visible squeezing of the liquid lipophilic phase out of the shrunk gel. 

Komarova GA, Starodubtsev SG, Lozinsky VI, Kalinina El, Landfester K, Khokhlov AR (2008) Intelligent gels and cryogels with entrapped emulsions. Langmuir 24 4467-4469... 

Lozinsky VI (2002) Cryogels on the basis of natural and synthetic polymers preparation, properties and application. Uspekhi Khimii 71 (6) 559—585... 

Efremenko, E., Votchitseva, Yu., Plieva, F., Galaev, T, and Mattiasson, B. (2006) Purifieation of Hisg-organophosphate hydrolase using monolithic supermacroporous polyacrylamide cryogels developed for immobilized metal affinity chromatography, Appl. Microbiol. Biot. 70(5) 558-563. 

Martynenko, N.N., Gracheva, I.M., Saiishvili, N.G., Zubov, A.L., ETRegistan, G.I., and Lozinsky, V.I. (2004). Immobilization of Champagne yeasts by inclusion into cryogels of polyvinil alcohol Means of preventing cell release from the carrier matrix. Appl. Biochem. Microbiol, 40, 158-164. 

Figure 1. Pore size disuibutions of (a) RF cryogels, (b) RF xerogels and (c) RF MW gels synthesized under the condition of R/C = 200.

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