Poly(vinyl alcohol) cryogels employed as matrices for cell immobilization. 2. Entrapped cells resemble porous fillers in their effects on the properties of PVA-cryogel carrier

Lozinsky, V. I.; Zubov, A. L.; Titova, E. F.

doi:10.1016/s0141-0229(96)00110-x

Cited by 88 publications

(51 citation statements)

References 16 publications

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“…PVA cryogels obtained by repeated freezing and melting were employed as matrices for cell immobilization, [7,8]. Some crosslinked PVA gels have also been obtained by irradiation with specific doses of gamma radiation, [9,10].…”

Section: Introductionmentioning

confidence: 99%

ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

et al. 2013

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Abstract:The effects of gamma radiation on the local structure of PVA membranes containing TiO 2 were investigated by ESR and XRD methods. An intense ESR signal is observed after irradiation at 16 KGy dose. This signal appears only for irradiated samples and it is associated with the breaking of the polymeric chain, followed by local reorganization of the polymeric segments and the apparition of the unpaired electrons and free radicals. The intensity of the signal decreases with the concentration of TiO 2 , indicating a shielding effect of the dopand. That the modification of local order of the polymeric chains has been modified after irradiation is confirmed by XRD method. PACS

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Section: Introductionmentioning

confidence: 99%

ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

et al. 2013

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“…(11) Macroporous PVA cryogels were proposed as cell, drug and protein carriers. (12,13) Agarose cryogel sponges were evaluated as scaffolds for culturing both isolated pancreatic islets and insulinoma cells. (14,15) Porous gelatin and chondroitin sulphate cryogels were selected as carriers for the culturing of a large variety of human cells (e.g.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cryogenic Treatment on the Rheological Properties of Gelatin Hydrogels

Vlierberghe

Dubruel

Schacht

2010

Journal of Bioactive and Compatible Polymers

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Above the critical gelation concentration, gelatin has the ability to form a gel when cooled below the sol-gel temperature. In the present work, freeze-thaw cycles were implemented on gelatin solutions possessing varying concentrations. The rheological properties of the cryogels developed were compared with hydrogels formed at room temperature. The results indicated that the rheological properties of cryogels were superior to those of the corresponding hydrogels formed at room temperature. In addition, the critical gelation concentration decreased after (repeated) cryo-treatment(s). The effect of applying various (cryo)parameters, including the number of freeze-thaw cycles, the cooling rate, the thawing rate and the gelatin concentration, on the final material properties was examined. The rheological properties of the cryogels improved with an increasing number of cryo-cycles and a decreasing cooling and thawing rate. In a second part of the work, methacrylamide-modified gelatin was treated cryogenically, followed by in situ UV-irradiation to enable radical crosslinking. It was shown that the crosslinking efficiency improved upon freeze-thawing. The latter was however limited by the gelatin concentration, which affects the chain mobility required to induce phase separation. The present work demonstrates that cryogelation offers possibilities to finetune the mechanical properties of hydrogels. The observed findings are of relevance for the field of tissue engineering, since this concept was previously applied for the development of porous gelatin hydrogels as biomaterials. In addition, a cryogenic treatment can be applied to a wide range of synthetic and natural polymers.-3 -

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“…It is then desirable that the enzyme carrier possess large surface area, high permeability, hydrophilic character, chemical, mechanical and thermal stability. There are several methods to minimize hindrance of enzyme diffusion to the hydrophilic carriers, including the selection of monomers and crosslinking agents which can modify both the porous structure and pore size of the gel and low-molecular weight polymers (Fokina et al, 1995;Lozinsky et al, 1997;Pizarro et al, 1997;Giuliano et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Poly vinyl alcoholhydrogel, is an example of polymer produced by γ-radiation polymerization that has showed (I): remarkable stability over a prolonged period in acidic, alkaline and saline media (II): PVA is a biologically compatible, non toxic, readily available and low cost polymer iii: PVA are highly resistant to biological degradation as well as being insensitive to a composition of working media i.e, the carriers (in contrast to alginate or carrageenan matrices) do not undergo undesirable weaking as a result of the presence of certain solutes in the media. ( Lozinsky et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Mucor racemosus NRRL 3631 lipase with different polymer carriers produced by radiation polymerization

Mostafa¹,

El-Hadi²

2010

MJM

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Lipase was partially purified from the culture supernatant of Mucor racemosus NRRL 3631. In an attempt to increase the enzyme stability, the enzyme was immobilized on poly (vinyl alcohol) PVA, radiation cross liked poly (vinyl alcohol/ vinyl pyrrolidone) PVA / PVP and poly (vinyl alcohol/ hydroxyethylmethacrylate) PVA/ HEMA hydrogels. The maximum immobilization yield (31.74 %) was obtained using PVA/ HEMA copolymer. The effect of the immobilization parameters on the enzyme such as the hydrogel composition, irradiation dose and the immobilization technique was performed. An optimum radiation dose of 15 kGy and hydrogel composition of 10 % PVA/ HEMA (9.6: 0.4 v/v) increased the immobilization yield to 60.3 %. Diffusion phenomena can be markedly increased the enzyme immobilization on the surface of the hydrogel. In this case the retained activity was approximately 81.5 % of that of the free enzyme. The profiles of immobilized enzyme activities at various pH values (4-9) and temperatures (30-80 °C) showed an overall higher stability for the immobilized enzyme than that for the free one. The half life values of the immobilized and free enzymes at 60 °C were 3.3 h and 1.73 h, respectively. The immobilized enzyme retained 69.2 % of its initial activity after three cycles.

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Poly(vinyl alcohol) cryogels employed as matrices for cell immobilization. 2. Entrapped cells resemble porous fillers in their effects on the properties of PVA-cryogel carrier

Cited by 88 publications

References 16 publications

ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

ESR and XRD investigation of effects induced by gamma radiation on PVA-TiO2 membranes

Effect of Cryogenic Treatment on the Rheological Properties of Gelatin Hydrogels

Immobilization of Mucor racemosus NRRL 3631 lipase with different polymer carriers produced by radiation polymerization

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