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    A Stream Washes Through the Caves...

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    Mesoscale characterization of supramolecular transient networks using SAXS and Rheology

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    Abstract: Hydrogels and, in particular, supramolecular hydrogels show promising properties for application in regenerative medicine because of their ability to adapt to the natural environment these materials are brought into. However, only few studies focus on the structure-property relationships in supramolecular hydrogels. Here, we study in detail both the structure and the mechanical properties of such a network, composed of poly(ethylene glycol), end-functionalized with ureido-pyrimidinone fourfold hydrogen bonding units. This network is responsive to triggers such as concentration, temperature and pH. To obtain more insight into the sol-gel transition of the system, both rheology and small-angle X-ray scattering (SAXS) are used. We show that the sol-gel transitions based on these three triggers, as measured by rheology, coincide with the appearance of a structural feature in SAXS. We attribute this feature to the presence of hydrophobic domains where cross-links are formed. These results provide more insight into the mechanism of network formation in these materials, which can be exploited for tailoring their behavior for biomedical applications, where one of the triggers discussed might be used

    Comparison of Chemical Composition and Colour Parameters of Different Mentha Genus Plants Grown under Organic Conditions

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    Mentha species are one of the world oldest and popular herbs, that are used in cosmetic and food industry, as well as tea for their medical properties. Due the consumer perception of ecological production and aromatic plants production waste utilization the objective of this work was to determine differences in chemical content and colour among different varieties and parts of Mentha plants ecologically grown in Lithuania. In mint leaves there were determined: content of essential oils, dry matter, soluble solids, ascorbic acid, crude fibre, crude ash, photosynthetic pigments and colour CIE L*a*b* parameters. In the case of mint plants stems, the same analyses were performed except ascorbic acid, soluble solids and colour. The highest content of essential oils were found in Mentha spicata L. ‘Moroccan’ and Mentha piperita L. ‘Glacialis’ leaves, while the least in Mentha suaveolens Ehrh. ‘Variegata’. The content of essential oils in the stems was minor and did not depend on mint variety. Plant parts differ significantly in respect of chemical composition. Amount of dry matter in mint leaves and stems was very similar, while crude ash in the leaves was twice higher than in the stems. Content of crude fibre in the leaves did not differ significantly in all investigated varieties and was 3.6 times lower comparing with the stems. Average ratio of chlorophyll a to b in the leaves was equal to 2.78, while in stems equal to 2.83. The lightest was Mentha suaveolens ‘Variegata’, the darkest Mentha spicata L. ‘Moroccan’ and the greenest Mentha piperita L. ‘Swiss’ leaves. Mints and their parts differ in chemical content and can have widespread usage not only for production of high-value natural products but in addition as alternative fibrous biomass plants

    Photopatternable, Branched Polymer Hydrogels Based on Linear Macromonomers for 3D Cell Culture Applications

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    Photochemical ligation strategies in hydrogel materials are crucial to model spatiotemporal phenomena that occur in the natural extracellular matrix. We here describe the use of cyclic 1,2-dithiolanes to cross-link with norbornene on linear poly(ethylene glycol) polymers through UV irradiation in a rapid and byproduct-free manner, resulting in branched macromolecular architectures and hydrogel materials from low-viscosity precursor solutions. Oscillatory rheology and NMR data indicate the one-pot formation of thioether and disulfide cross-links. Spatial and temporal control of the hydrogel mechanical properties and functionality was demonstrated by oscillatory rheology and confocal microscopy. A cytocompatible response of NIH 3T3 fibroblasts was observed within these materials, providing a foothold for further exploration of this photoactive cross-linking moiety in the biomedical field.Supramolecular & Biomaterials Chemistr
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