1,721,215 research outputs found
Un nuovo materiale superassorbente biodegradabile per le coltivazioni nelle regioni aride del Mezzogiorno
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Tuning the Porosity of Collagen-based Scaffolds for Use as Nerve Regenerative Templates
No full textRegenerative medicine aims at inducing the formation of physiological tissues, in cases where the spontaneous healing response following a severe injury or disease leads to wound closure via contraction and synthesis of scar or fibrotic tissue. The suppression of both wound contraction and scar synthesis, with the simultaneous synthesis of physiological tissues, might be achieved by implanting a porous macromolecular scaffold within the site of injury, able to host cells and guide their behavior toward regeneration. Tubular scaffolds, reconnecting the proximal and distal stumps of a transected peripheral nerve, demonstrated to be able to induce regeneration of the lost nerve trunk. Experimental evidence from independent investigations shows that protein-permeable porous tubes, of different types, perform better as regenerative templates when their pore size is also cell-permeable (>10 mu m). Moreover, the regenerative potential of the porous conduit may be further enhanced when inserting a substrate with longitudinally oriented pores within it, since such an oriented construct provides physical support and guide to the growth of neural structures across the site of injury. This study focused on the production of collagen-based conduits and matrices with a micropatterned porosity, suitable for use as nerve regenerative templates. The manufacturing techniques for the production of tubular and cylindrical scaffolds, with controlled pore size and orientation, were based on a freeze-drying process. Tubular scaffolds possessed a radially oriented porosity with a radial gradient of pore sizes, ranging from cell-permeable pores at the inner tube wall to cell-impermeable pores at the outer one. Cylindrical scaffolds exhibited nearly axially oriented pores, with a pore size depending on the freezing rate as well as on the collagen concentration. Due to their peculiar porous structures, such scaffolds are expected to enhance the regenerative capacity of transected peripheral nerves as well as to lead to a better understanding of the cellular mechanisms underlying peripheral nerve regeneration
Concurrent effect of microporosity and chemical structure on the equilibrium sorption properties of cellulose-based hydrogels
No full textPolyelectrolite hydrogels are crosslinked polymers which display high sorption capacity in water and water solutions. They are widely used in the marked of personal hygiene products, as well as in other biomedical and industrial applications. In the most industrial application they are not biodegradable and prepared starting from acrylamide. In this work, the chemical-physical analysis of a novel class of natural polymers-based microporous superabsorbent hydrogels has been presented. The main focus is the definition of the relationship between material's chemical-physical structure and its equilibrium sorption properties. The effect of the variation of the degree of crosslinking, the polyelectrolyte nature of the backbone and the hydrogel microporosity on its swelling properties has been analysed, and a good agreement with the theoretical statements has been displayed. The effect of the ionic strength and the pH of the external solution in contact with the hydrogel on its equilibrium sorption properties has also been assessed, and an high sensitivity to these variations was detected for all the tested chemical compositions and physical structures. This work have to be considered part of the efforts towards the reduction of the environmental impact of the large scale consumption industrial polymer based products
Monitoring of manufacturing process of new superabsorbents by measurement of mixing stress during crosslinking reaction
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