A Spontaneous In Situ Thiol-Ene Crosslinking Hydrogel with Thermo-Responsive Mechanical Properties
Andreas Aerts,
Maxim Vovchenko,
Seyed Ali Elahi,
Rocío Castro Viñuelas,
Tess De Maeseneer,
Martin Purino,
Richard Hoogenboom,
Hans Van Oosterwyck,
Ilse Jonkers,
Ruth Cardinaels,
Mario Smet
Affiliations
Andreas Aerts
Laboratory of Organic Material Synthesis, Polymer Chemistry and Materials, Department of Chemistry, KU Leuven, Celestijnenlaan 200f, P.O. Box 2404, 3001 Leuven, Belgium
Maxim Vovchenko
Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300C, P.O. Box 2419, 3001 Leuven, Belgium
Seyed Ali Elahi
Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300C, P.O. Box 2419, 3001 Leuven, Belgium
Rocío Castro Viñuelas
Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven Tervuursevest 101, P.O. Box 1501, 3001 Leuven, Belgium
Tess De Maeseneer
Rheology and Technology, Soft Matter, Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200J, P.O. Box 2424, 3001 Leuven, Belgium
Martin Purino
Supramolecular Chemistry Group, Department of Organic and Macromolecular Chemistry, UGent, Krijgslaan 281, Building S4, 9000 Ghent, Belgium
Richard Hoogenboom
Supramolecular Chemistry Group, Department of Organic and Macromolecular Chemistry, UGent, Krijgslaan 281, Building S4, 9000 Ghent, Belgium
Hans Van Oosterwyck
Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300C, P.O. Box 2419, 3001 Leuven, Belgium
Ilse Jonkers
Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven Tervuursevest 101, P.O. Box 1501, 3001 Leuven, Belgium
Ruth Cardinaels
Rheology and Technology, Soft Matter, Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200J, P.O. Box 2424, 3001 Leuven, Belgium
Mario Smet
Laboratory of Organic Material Synthesis, Polymer Chemistry and Materials, Department of Chemistry, KU Leuven, Celestijnenlaan 200f, P.O. Box 2404, 3001 Leuven, Belgium
The thermo-responsive behavior of Poly(N-isopropylacrylamide) makes it an ideal candidate to easily embed cells and allows the polymer mixture to be injected. However, P(NiPAAm) hydrogels possess minor mechanical properties. To increase the mechanical properties, a covalent bond is introduced into the P(NIPAAm) network through a biocompatible thiol-ene click-reaction by mixing two polymer solutions. Co-polymers with variable thiol or acrylate groups to thermo-responsive co-monomer ratios, ranging from 1% to 10%, were synthesized. Precise control of the crosslink density allowed customization of the hydrogel’s mechanical properties to match different tissue stiffness levels. Increasing the temperature of the hydrogel above its transition temperature of 31 °C induced the formation of additional physical interactions. These additional interactions both further increased the stiffness of the material and impacted its relaxation behavior. The developed optimized hydrogels reach stiffnesses more than ten times higher compared to the state of the art using similar polymers. Furthermore, when adding cells to the precursor polymer solutions, homogeneous thermo-responsive hydrogels with good cell viability were created upon mixing. In future work, the influence of the mechanical micro-environment on the cell’s behavior can be studied in vitro in a continuous manner by changing the incubation temperature.
