Hydrogels are water swollen networks of polymers and especially hydrogels consisting of poly vinylpyrrolidone/poly ethyleneglycol-dimethacrylate (PVP/PEG-DMA) blends show promising wound care properties. Enhanced functionality of the hydrogels can be achieved by incorporating drugs and other substances that may assist wound healing into the gel matrix. Controlling the release of active compounds from the hydrogels may be possible by carefully modifying the polymer matrix. For this purpose, cyclodextrins (CD) were grafted to the polymer matrix in 4-5 w/w% in an attempt to retard the release of water-soluble drugs. Ibuprofenate (IBU) was chosen as model drug and loaded in IBU/CD ratios of 0.6, 1.2, and 2.5. Vinyl derivatives of α-, β-and γ-CD were produced, added to the prepolymer blend and cured by UV-light. During this curing process the CD derivatives were covalently incorporated into the hydrogel matrix. The modified hydrogels were loaded with ibuprofenate by swelling. The release of the model drug from CD modified hydrogels show that especially covalently bonded β-cyclodextrin can change both the release rate and the release profile of ibuprofen.
Phycocyanins are pigment-protein complexes with potential application as natural food colourants. The perceived colour of phycocyanins varies with pH, and a method to stabilise the colour over a broad range of pH values is requested by the food industry. In this work, the stabilising effect of sodium dodecyl sulphate (SDS) micelles on pH-induced colour variations of phycocyanin was examined. SDS was shown to stabilise the blue conformation of phycocyanin, preventing formation of the green conformation, which is prevalent at low pH. The studies indicated that the stabilising effect occurred through interaction or entrapment of the non-protonated, circular helical (blue) structure of phycocyanin and the anionic SDS micelles. The interaction prevented conversion into protonated, partially unfolded (green) phycocyanin species. This information opens for new possibilities to stabilise the blue conformation of phycocyanin and to apply the stabilised form in food products as a natural blue food colourant.
This article concerns the concept of selfhood in Kierkegaard’s thinking. First, it rejects any scholarly attempt to establish an essentialist metaphysics of selfhood in Kierkegaard; instead, it seeks to show how the author himself develops his thoughts on subjectivity by applying numerous literary figures and a good deal of irony. Secondly, the article underpins this reading by displaying a specific figure, “The Walking One,” that indicates that actual and individual existence is to be completed only in an actual and individual movement. From here, “The Walking One” opens up new vistas to recognition, communication and language-however, in a paradoxical way. This is proved through analyses of Philosophical Fragments (1844), The Sickness unto Death (1849) and also an upbuilding discourse “He is Believed in the World” (1847). In this light, it is argued that Kierkegaard performs a subtle dialectics between standstill and walking or between “break” and “practice.”
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