Hydrogel

Résumé

vignette|Hydrogel. Un hydrogel est un gel dans lequel l'agent gonflant est l'eau. La matrice d'un hydrogel est généralement un réseau de polymères. Ces derniers sont insolubles dans l'eau, mais sont capables de gonfler substantiellement en présence d'une grande quantité d'eau ou de solutions aqueuses telles que les fluides biologiques. Les polymères utilisés pour fabriquer un hydrogel peuvent être superabsorbants. Il a diverses applications biomédicales notamment dans les systèmes de délivrance de médicaments, dans le traitement de brûlures cutanées et dans les lentilles de contact souples. Il peut être imprimé en 3D. Des hydrogels existent dans la nature avec comme exemples des mucilages fongiques, les œufs de grenouilles et de crapauds (qui gonflent au contact de l'eau) ou le mucus filmo-filamenteux défensif des myxines. Formation Lors de la réticulation, les chaînes polymères rendues hydrosolubles par la présence de groupements hydrophiles se connectent entre elles vi

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https://fr.wikipedia.org/wiki/Hydrogel

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This course covers the fundamental concepts behind the design, function and application of state-of-the-art biomaterials, that is, materials that are designed based on a molecular understanding of their interactions with biological systems.

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In this dissertation, we investigated the effect of poly(ethylene glycol) hydrogel network structures on various cellular activities such as proliferation and matrix production using chondrocytes as a cell source. We have used various methods to alter the network structure, which involves utilizing precursors with varying molecular weight and changing the degree of polymerization. The latter was achieved by varying initiator concentrations, and duration of polymerization time. PEG hydrogels constituting PEG precursors of molecular weights 3.4kDa, 6kDa, 10kDa and 20KDa were synthesized, characterized and subsequently tested for their effects on chondrocytes biosynthetic activity. The structural parameters of the hydrogel network that varied due to our experimental differences were determined. Specifically, the hydrogel structures were characterized in terms of swelling ratio, the molecular weight between crosslinks, the mesh size, and the pore size. Swelling ratio of the hydrogels decreased while gel content increased with longer UV exposure and higher photo-initiator concentration. High compressive modulus was observed with PEG 3.4kDa whereas PEG 20kDa exhibited high ultimate stress, which was 37 times higher than the other hydrogels. Cells in hydrogels with a lower MW (PEG3.4) showed higher proliferation and more ECM synthesis in comparison with high molecular weight PEG hydrogels. This could be attributed to the bigger pore size of the high molecular weight PEG hydrogels, which could result in loss of cells. However, the amount of DNA observed after week 4 normalized to day 1 revealed that cells in hydrogels with a higher MW showed a higher proliferation and the amount of ECM synthesized per cell was larger. Histology revealed that proteoglycans were more diffused in the matrix with higher MW, indicating the presence of higher pore size. Cellular aggregation was observed after 2 weeks in all the hydrogels except for the 3.4kDa hydrogels; the aggregation of cells in 20kDa was also very minimal. A low degree of polymerization led to a high proliferation rate during the first week followed by enhanced ECM production. Conversely, a high degree of polymerization led the cells to a greater amount of protein synthesis during the first week, followed by proliferation. While the cells behaved in different ways at early time points of the culture, at the end of 4 weeks, there was no significant difference between the number of cells, nor ECM production in different hydrogels. This study clearly shows that the network structure has a temporal effect on chondrocyte functions

2009

Chargement

Photocured Nanocellulose Composites: Recent Advances

Julien Bras, Yves Leterrier, Mohammed Arif Poothanari, Aigoul Schreier

This perspective gives an overview of recent progress in thefield of photocured polymer composites based on variousforms of nanocelluloses, with a focus on cellulose nanofibrils. The manufacturing processes and performances of these nanocellulosecomposites are detailed, comprising solvent-assisted mixing processes, emulsification, coating and casting processes, preformimpregnation, and 3D printing. Attention is also paid to life-cycle engineered approaches to improve their sustainability. Thesematerialsfind applications in numerous domains, primarily as protective coatings but also as diffusion barrier composites andfilmsfor packaging and encapsulation of electronics, as composite hydrogels for biomedical applications, and as membranes for battery technologies.

AMER CHEMICAL SOC2022

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Replacement of the nucleus pulposus by a composite hydrogel

Ana Borges de Couraça

2009

Chargement

2009