Engineering and Functionalization of Hemicellulose Hydrogels
Sammanfattning: Hemicellulose is the second most abundant component in wood and is an important renewable resource that is used in films, paper composites and biofuels. Hemicelluloses have several advantages, including their abundance, degradability and renewability. O-acetyl-galactoglucomannan (AcGGM) is a type of hemicellulose that is predominantly found in softwood specimens. In the recent drive to engineer functional hydrogels with stimuli-responsive properties, functional AcGGM-derived hydrogels are highly interesting alternatives. In the first part of this thesis, a combination of the electro-activity of conducting oligomers and AcGGM was used to design a robust pathway to generate electrically conductive hemicellulose hydrogels (ECHHs) using AcGGM and a conductive aniline tetramer. Subsequently, in order to fabricate ECHHs using a greener and more facile approach, a one-pot reaction was performed in which AcGGM was cross-linked with epichlorohydrin in the presence of a conductive aniline pentamer in water at ambient temperature. To impart other functionalities to the hemicellulose hydrogels, magnetic field-responsive hemicellulose hydrogels (MFRHHs) were fabricated by simultaneous in situ formation of magnetic Fe 3 O 4 and cross-linking of AcGGM. These MFRHHs exhibited a controlled release of the protein bovine serum albumin. Finally, a facile, fast and functional chemical methodology to prepare stimuli-responsive hemicellulose micro-gels was developed that offers the potential for fabricating hydrogels using a green processing technique. The micro-gels were shown to have a rapid response to electrochemical stimuli, pH alterations and a magnetic field, as well as good blood compatibility, which is required for biomedical applications. All these stimuli-responsive hemicellulose hydrogels demonstrated controllable aqueous swelling behavior and combine the renewability of hemicellulose and stimuli-responsiveness of functional molecules, thereby opening new potential routes to fabricate biomaterials with a wide range of applications (e.g., biosensors, nerve system repair, and controlled drug release).
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