Functional and Renewable Galactoglucomannan-based Hydrogels

Sammanfattning: Polysaccharides represent an important resource for a variety of products, from food via fuel supply to functional materials of every kind. Here they are, due to their natural diversity found in many special applications, e.g. in the biomedical sector.Lately, a fairly unused group of polysaccharides, so called hemicelluloses, attracts more and more attention due to its high availability and promising properties.This thesis presents the utilization of the water-soluble species O-acetyl-galactoglucomannan (AcGGM),   derived from softwood, as raw material for the synthetic design of functional hydrogels. AcGGM was used thanks to its great availability and high hydrophilicity rendering it an excellent material for hydrogels design.For this purpose, a three-step-method was devised consisting of (1) the carbonyldiimidazole activation of primary hydroxylated vinylic compounds, (2) the substitution of hydroxyl groups of the AcGGM backbone with vinylic functions, and (3) radical crosslinking yielding in a hydrophilic three-dimensional network – a hydrogel.Crosslinking strategies were varied from photo-crosslinking in DMSO to redox-initiated crosslinking in H2O with the objective of adapting the synthesis to benign conditions. Varying the crosslinking-species as well as the media was found to have a significant influence on the resulting gels’ properties, such as swelling capacity and G-modulus.  Here, swelling capacity could be affected to vary between ~0.6 to ~23 times of the gels self-weight and the G-modulus ranged from 0.4 to 145 kPa.AcGGM and 2-hydroxy ethyl methacrylate (HEMA) gels were studied further and evaluated for their suitability as drug delivery systems for two model drugs (caffeine and Vitasyn Blue) varying in size, polarity and hydrophilicity. Here, the gels’ composition as well as a second modification with maleic acid anhydride was proved to affect the release properties significantly.Based on our findings we conclude that the presented library is an important step to the promising future of these hydrogels based on the renewable resource AcGGM.