University of Twente Student Theses


A supramolecular hydrogel system for 3D embedded bioprinting

Hartog, Tessa G. den (2019) A supramolecular hydrogel system for 3D embedded bioprinting.

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Abstract:Biofabrication via three-dimensional bioprinting enables simultaneous and spatial positioning of cells, materials and bioactive factors. Hydrogel-based materials for embedded bioprinting have been introduced, nevertheless it is still challenging to include all the requirements of a bioink into a single biomaterial. Key factors in designing these biomaterials are the mechanical strength to ensure shape fidelity, the ability to flow under an applied shear strain (shear-thinning) and the capacity to remodel and recover from potential mechanical induced damage (self-healing). Herein, this work reports a novel biomaterial compatible with 3D embedded bioprinting based on supramolecular host-guest interactions between β-cyclodextrin (βCD, host) and tyramine (TA, guest) conjugated to either dextran or 8arm-PEG. Mechanical strength is obtained by enzymatic crosslinking of tyramine using horseradish peroxidase (HRP) as a catalyst and hydrogen peroxide (H2O2) as an oxidant. Adamantane (Ada) was as well conjugated to 8arm-PEG in order to compare physical crosslinking of our βCD/TA system with βCD/Ada systems. Mixing βCD conjugated polymers with tyramine conjugated polymers did not result in hydrogels whereas mixtures with PEG-Ada as guest led to viscous hydrogel formation. Determination of the stoichiometry confirmed 1:1 H:G molar ratio binding between both βCD/TA and βCD/Ada complexations with a strong association constant for βCD/Ada complexation and a weak association constant for βCD/TA. The HRP/TA and H2O2/TA ratios need to be optimized in order to sufficiently crosslink the tyramines and make stable hydrogels. In conclusion, the supramolecular host-guest interactions between βCD and tyramine proved insufficient to physically crosslink the polymers and mixing them did therefore not result in a stable hydrogels. Further research is needed to design new polymers that are compatible with embedded bioprinting and could offer the desired physically crosslinked hydrogel while preserving the option of enzymatic crosslinking of the tyramines.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:35 chemistry, 42 biology, 51 materials science
Programme:Biomedical Engineering MSc (66226)
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