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2022
Journal Article
Title
Quantifying the Adhesion of Hydrogels to Polymers for the Fabrication of Hybrid Biomaterial Constructs
Abstract
Introduction:
In tissue engineering, hydrogels represent a promising class of materials for the direct cell environment. To create complex, dimensionally stable structures that can withstand mechanical stress, hydrogels are reinforced with polymer scaffolds. From this arise two important research questions: How forms the hydrogel a stable bond with the polymer scaffold? How can this be quantified? We present a model system of a PVP-co-GMA-enhanced fibrin-based hydrogel and thiolene-based polymer scaffolds from 3D printing to investigate these questions. The epoxy function in the GMA portion of the copolymer is expected to enable covalent bonding to free thiol groups on the surface of the polymer scaffolds.
Methods:
Thiol-ene-polymers and the accessibility of thiol groups were characterized by FTIR-, XPS-spectroscopy and fluorescence microscopy. To quantify the hydrogel bonding to the polymer scaffold, two polymer parts were bonded with a defined amount of hydrogel under different conditions and investigated by single-lap-shear-test. Dry and wet bonding, bonding time, surface pretreatment, and hydrogel composition were varied.
Results:
Thiol-ene-polymers of various compositions were prepared and availability of free thiol groups was demonstrated. Methods for chemical bonding and bonding quantification of fibrin gels to the polymer surface were established. While dry bonding resulted in adhesion strengths between 9-42kPa, wet bondings achieved 2-33kPa depending on the combination and composition of the thiol-ene-polymer and hydrogel, with the highest values found for samples of intermediate thiol and GMA composition. Coating of the polymers with PVP-co-GMA increased adhesion strength by 60% over uncoated samples.
Conclusion:
Knowledge of the bonding behavior is essential for the fabrication of hybrid constructs of hydrogels and polymer scaffolds. Optimal bonding is not necessarily achieved by maximum availability of surface groups and corresponding anchor groups in the hydrogel. Prior coating of the polymer scaffolds leads to stronger bonding and thus presumably to better integration of the hydrogel.
In tissue engineering, hydrogels represent a promising class of materials for the direct cell environment. To create complex, dimensionally stable structures that can withstand mechanical stress, hydrogels are reinforced with polymer scaffolds. From this arise two important research questions: How forms the hydrogel a stable bond with the polymer scaffold? How can this be quantified? We present a model system of a PVP-co-GMA-enhanced fibrin-based hydrogel and thiolene-based polymer scaffolds from 3D printing to investigate these questions. The epoxy function in the GMA portion of the copolymer is expected to enable covalent bonding to free thiol groups on the surface of the polymer scaffolds.
Methods:
Thiol-ene-polymers and the accessibility of thiol groups were characterized by FTIR-, XPS-spectroscopy and fluorescence microscopy. To quantify the hydrogel bonding to the polymer scaffold, two polymer parts were bonded with a defined amount of hydrogel under different conditions and investigated by single-lap-shear-test. Dry and wet bonding, bonding time, surface pretreatment, and hydrogel composition were varied.
Results:
Thiol-ene-polymers of various compositions were prepared and availability of free thiol groups was demonstrated. Methods for chemical bonding and bonding quantification of fibrin gels to the polymer surface were established. While dry bonding resulted in adhesion strengths between 9-42kPa, wet bondings achieved 2-33kPa depending on the combination and composition of the thiol-ene-polymer and hydrogel, with the highest values found for samples of intermediate thiol and GMA composition. Coating of the polymers with PVP-co-GMA increased adhesion strength by 60% over uncoated samples.
Conclusion:
Knowledge of the bonding behavior is essential for the fabrication of hybrid constructs of hydrogels and polymer scaffolds. Optimal bonding is not necessarily achieved by maximum availability of surface groups and corresponding anchor groups in the hydrogel. Prior coating of the polymer scaffolds leads to stronger bonding and thus presumably to better integration of the hydrogel.
Author(s)
Al Enezy-Ulbrich, Miriam Aischa
RWTH Aachen University, Institute for Technical and Macromolecular Chemistry, Research Area Functional and Interactive Polymers
Pich, Andrij
RWTH Aachen University, Institute for Technical and Macromolecular Chemistry, Research Area Functional and Interactive Polymer