| 1. |
- Aragao, Rosa, et al.
(författare)
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Immobilization of Clostridium acetobutylicum DSM 792 as macroporous aggregates through cryogelation for butanol production
- 2014
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1873-3298 .- 1359-5113. ; 49:1, s. 10-18
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a new cell immobilization technique is presented. Cells of Clostridium acetobutylicum DSM 792 form a macroporous aggregate through cryogelation with concomitant crosslinking together with activated polyethyleneimine (PEI) and poly(vinyl alcohol) (PVA). The cell based cryogel presents a highly porous, elastic structure with walls consisting of densely packed crosslinked cells. The immobilization process maintained the viability of cells as new bacterial cells were observed when gel-plugs were incubated in liquid medium, glucose was consumed and solvent production was observed. Solvent production was improved 2.7-fold in immobilized cells in comparison to free cells. It was possible to reuse the gel-plugs 3-5 times in partial or completely fresh medium, reaching a maximum butanol concentration in the broth of 18.2 g/l and yield of 0.41 (g/g) in one of the cycles. The use of cells based cryogels can be a good alternative for improvement of acetone-butanol-ethanol (ABE) process as cells are immobilized in a macroporous structure with low limitations for mass transfer with potential for high yield production. (C) 2013 Elsevier Ltd. All rights reserved.
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| 2. |
- Berillo, Dmitry, et al.
(författare)
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Cryogelation of Chitosan Using Noble-Metal Ions: In Situ Formation of Nanoparticles.
- 2014
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 15:6, s. 2246-2255
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Tidskriftsartikel (refereegranskat)abstract
- One of the purposes of the project was to develop the method of preparation of 3D macroporous hydrogel with a structure of interconnected pores by the use of noncovalent interactions. The combination of chitosan and noble-metal complexes was investigated as cross-linking agents for the preparation of ionic cryogels (ICs). Furthermore, the treatment of the ICs containing gold complex by glutaraldehyde results in spontaneous formation of gold nanoparticles (AuNPs) and chemical cross-linking of the cryogel. The characterization of prepared macroporous materials was carried out by the use of FTIR, SEM, TEM techniques, and texture analyzer. A new strategy for control of size distribution of AuNPs was suggested. The size distribution of obtained AuNPs and their population inside of walls of cryogels was estimated. A method for quantifying unreacted chloroauric acid in the presence of acetic acid was proposed. The possibility of use of prepared cryogels with immobilized AuNPs as a catalytic flow through reactor is shown.
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| 3. |
- Berillo, Dmitry, et al.
(författare)
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Formation of macroporous self-assembled hydrogels through cryogelation of Fmoc-Phe-Phe.
- 2012
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 368:1, s. 226-230
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Tidskriftsartikel (refereegranskat)abstract
- In this study, it was found that macroporous hydrogels were formed when self-assembly of fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) peptides was induced using glucono-δ-lactone (GdL) in apparently frozen samples. Formed cryogels exhibited a heterogeneous structure with pore walls of densely packed fibres of assembled dipeptides and pores in the range 10-100μm. Hydrogels formed from the same composition above the freezing point exhibited a homogenous structure without any apparent porosity. The formed gels were characterised using microscopy techniques, CD-spectroscopy and stress sweeps. The cryogels exhibited less mechanical strength than the hydrogels that might be due to the heterogeneous structure of the former. It appeared that the self-assembled peptide both in the cryo- and hydrogel maintained the β-sheet structure commonly attributed to these.
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| 4. |
- Guzmán, Daniel, et al.
(författare)
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Preparation of hydrophilic poly(3-hydroxybutyrate) macroporous scaffolds through enzyme-mediated modifications
- 2011
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Ingår i: Journal of Bioactive and Compatible Polymers. - : SAGE Publications. - 0883-9115 .- 1530-8030. ; 26:5, s. 452-463
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Tidskriftsartikel (refereegranskat)abstract
- Scaffolds made from poly(3-hydroxybutyrate) were prepared by thermally induced phase separation from solutions in dioxane at temperatures above (23 degrees C) or below the freezing point of the solvent. At 23 degrees C, gelation occured with nano-fibrous network formation. The scaffolds prepared at -12 degrees C and -25 degrees C exhibited a highly porous morphology, with pores in the range of 3-25 mu m, caused by freezing of dioxane. The macroporous scaffolds, prepared at -12 degrees C, were treated with lipase to generate functional groups to which gelatin and glucosamine, respectively, were chemically coupled. The modified scaffolds had lower molecular weight, higher water content, lower melting temperature, and enthalpy. Cultivation of human embryonic fibroblasts on the macroporous scaffolds confirmed that the cells proliferated and adhered to the materials.
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| 5. |
- Hajizadeh, Solmaz, et al.
(författare)
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Characterization of macroporous carbon-cryostructured particle gel, an adsorbent for small organic molecules
- 2010
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 6:21, s. 5562-5569
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Tidskriftsartikel (refereegranskat)abstract
- Preparation of a new type of cryostructured carbon particle macroporous gel with one-step sub-zero cross-linking was studied in this work. Aggregation of nano-and micro-particles of poly(N-isopropylacrylamide-co-allylamine) was used to form a polymeric network to integrate activated carbon particles. The cryostructured particle gel was compared with the conventional composite cryogel. The unique macroporous structure of the gel in combination with retained porosity of the carbon particles makes it suitable in separation and environmental applications. The adsorption isotherm of phenol was studied and the advantages of cryostructured particle gel over conventional composite structures were compared in this study. The developed new gels were characterized by scanning electron microscopy, mercury porosimetry and texture analysis.
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| 6. |
- Hajizadeh, Solmaz, et al.
(författare)
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Composite cryogel with immobilized concanavalin A for affinity chromatography of glycoproteins.
- 2012
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Ingår i: Journal of Separation Science. - : Wiley. - 1615-9314 .- 1615-9306. ; 35:21, s. 2978-2985
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Tidskriftsartikel (refereegranskat)abstract
- Composite cryogels containing porous adsorbent particles were prepared under cryogelation conditions. The composites with immobilized concanavalin A (Con A) were used for capturing glycoproteins. Adsorbent particles were introduced into the structure in order to improve the capacity and to facilitate the handling of the particles. The monolithic composite cryogels were produced from suspensions of polyvinyl alcohol particles and porous adsorbent particles and cross-linked under acidic conditions at sub-zero temperature. The cryogels were epoxy activated and Con A was immobilized as an affinity ligand. Binding and elution of horseradish peroxidase (HRP) was studied in batch experiment and in a chromatographic setup. Increasing adsorbent concentration in composite cryogels will increase ligand density, which therefore enhances the amount of bound HRP from 0.98 till 2.9 (milligram enzyme per milliliter of gel) in the chromatographic system. The material was evaluated in 10 cycles for binding and elution of HRP.
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| 7. |
- Hajizadeh, Solmaz, et al.
(författare)
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Cryogelation of molecularly imprinted nanoparticles: A macroporous structure as affinity chromatography column for removal of β-blockers from complex samples.
- 2013
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Ingår i: Journal of chromatography. A. - : Elsevier BV. - 1873-3778 .- 0021-9673. ; 1274, s. 6-12
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a new macroporous molecularly imprinted cryogel (MIP composite cryogel) was synthesized by glutaraldehyde cross-linking reaction of poly(vinyl alcohol) (PVA) particles and amino-modified molecularly imprinted core-shell nanoparticles. The MIP core-shell nanoparticles were prepared using propranolol as a template by one-pot precipitation polymerization with sequential monomer addition. The characteristics of the MIP composite cryogel were studied by scanning electron microscopy (SEM) and texture analyzer. The macroporous structure of the composite (with the pore size varying from a few micrometers to 100μm) enabled high mass transfer of particulate-containing fluids. In a solid phase extraction (SPE) process, the efficiency and selectivity of the MIP composite cryogel were investigated, where the cryogel was used as an affinity matrix to remove propranolol from aqueous solution as well as from complex plasma sample without prior protein precipitation. The MIP composite cryogel maintained high selectivity and stability and could be used repeatedly after regeneration.
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| 8. |
- Hajizadeh, Solmaz, et al.
(författare)
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Evaluation of selective composite cryogel for bromate removal from drinking water.
- 2010
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Ingår i: Journal of Separation Science. - : Wiley. - 1615-9314 .- 1615-9306. ; 33, s. 1752-1759
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Tidskriftsartikel (refereegranskat)abstract
- Bromate, which is a potential carcinogen, should be removed from drinking water to levels of less than 10 mug/L. A chitosan-based molecularly imprinted polymer (MIP) and a sol-gel ion-exchange double hydrous oxide (Fe(2)O(3).Al(2)O(3).xH(2)O) adsorbent (inorganic adsorbent) were prepared for this purpose. The sorption behavior of each adsorbent including sorption kinetics, isotherms, effect of pH and selective sorption were investigated in detail. Sorption experimental results showed that the MIP adsorbents had better selectivity for bromate, even in the presence of high concentrations of nitrate, as compared to the inorganic adsorbent. It was found that pH does not affect the adsorption of bromate when using the inorganic adsorbent. Additionally, both adsorbents were immobilized in a polymeric cryogel inside plastic carriers to make them more practical for using in larger scale. Regeneration of the cryogels either containing MIP or inorganic adsorbents were carried out by 0.1 M NaOH and 0.1 M NaCl, respectively. It was found that the regenerated MIP and inorganic adsorbents could be used at least three and five times, respectively, without any loss in their sorption capacity.
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| 9. |
- Hajizadeh, Solmaz, et al.
(författare)
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Flow-Through-Mediated Surface Immobilization of Sub-Micrometre Particles in Monolithic Cryogels
- 2014
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Ingår i: Macromolecular Materials and Engineering. - : Wiley. - 1438-7492. ; 299:5, s. 631-638
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Tidskriftsartikel (refereegranskat)abstract
- Particles with functional groups on their surface were immobilized on premade cryogels through covalent bonding to maximize the accessibility of the target molecules to the surface of the particles. The physical properties of the composite cryogel were characterized by SEM, texture analysis and nitrogen adsorption. Different key factors affecting immobilization were also investigated, e.g., recirculation time and the number of functional groups on the premade cryogels. It was found that the physical characteristics of the composite cryogels prepared in this way were very similar to those of the primary matrices, while their binding capacity increased in comparison with conventionally prepared composite cryogels. The binding capacities of two different types of composite cryogel were evaluated by studying the adsorption of small molecules (copper ions and Orange G) and a large molecule (thermostable His-tagged exoglucanase).
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| 10. |
- Inci, Ilyas, et al.
(författare)
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Gelatin cryogels crosslinked with oxidized dextran and containing freshly formed hydroxyapatite as potential bone tissue-engineering scaffolds
- 2013
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Ingår i: Journal of Tissue Engineering and Regenerative Medicine. - : Hindawi Limited. - 1932-6254. ; 7:7, s. 584-588
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Tidskriftsartikel (refereegranskat)abstract
- Gelatin-based cryogels were prepared by using a novel crosslinker, oxidized dextran, which was synthesized and used in the study. The cryogels were also loaded with freshly formed hydroxyapatite (HA) particles. These cryogels are opaque, spongy and highly elastic and have a pore structure with large interconnected pores. They swell about 500% in aqueous media and within a few minutes reach their final swollen forms. The elastic moduli of HA-containing cryogels were 18.5 +/- 3.0 kPa, which is suitable for non-load-bearing bone tissue-engineering (TE) applications, especially for the craniofacial area. Copyright (c) 2012 John Wiley & Sons, Ltd.
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