- Redox-Responsive Degradable PEG Cryogels as Potential Cell Scaffolds in Tissue Engineering
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A Michael addition strategy involving the reaction between a maleimide double bond and amine groups is investigated for the synthesis of cryogels at subzero temperature. Low-molecular-weight PEG-based building blocks with amine end groups and disulfide-containing building blocks with maleimide end groups are combined to synthesize redox-responsive PEG cryogels. The cryogels exhibit an interconnected macroporous morphology, a high compressive modulus and gelation yields of around 95%. While the cryogels are stable under physiological conditions, complete dissolution of the cryogels into water-soluble products is obtained in the presence of a reducing agent (glutathione) in the medium. Cell seeding experiments and toxicologic analysis demonstrate their potential as scaffolds in tissue engineering.
- Dispinar, Tugba,Van Camp, Wim,De Cock, Liesbeth J.,De Geest, Bruno G.,Du Prez, Filip E.
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experimental part
p. 383 - 394
(2012/06/30)
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- Reversible uncoupling of photophosphorylation by a new bifunctional maleimide.
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A new bifunctional maleimide that contains a disulfide bond has been synthesized. This maleimide, dithiobis-N-ethylmaleimide (DTEM), like another bifunctional maleimide, o-phenylenebismaleimide, is about 500-fold more effective as an inhibitor of photophosphorylation than N-ethylmaleimide. Thylakoids must be illuminated in the presence of DTEM before the assay of phosphorylation for the inhibition to occur. Phosphoryalation in thylakoids treated with DTEM in the light is uncoupled and proton permeability of the treated thylakoids is enhanced. This uncoupling of photophosphorylation in thylakoids treated with DTEM can be reversed by thiol compounds. The addition of 50 mM dithiothreitol restores H+ uptake in thylakoids treated with DTEM in the light to control levels and partially reverses the inhibition of phosphorylation. Evidence is provided to show that DTEM cross-links groups within the gamma subunit of the coupling factor 1, and that the cross-link is broken by high concentrations of thiols. These results suggest that cross-linking is the cause for the increased proton permeability in thylakoids treated with bifunctional maleimides in the light.
- Moroney,McCarty
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p. 8951 - 8955
(2007/10/11)
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