Mechanisms of pore formation in hydrogel scaffolds textured by freeze-drying
| Autor: | Fabrice Barou, Hervé Duval, Jérôme Grenier, Bertrand David, Didier Letourneur, Pin Lv |
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| Přispěvatelé: | Laboratoire de Génie des Procédés et Matériaux - EA 4038 (LGPM), CentraleSupélec, Laboratoire de mécanique des sols, structures et matériaux (MSSMat), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Recherche Vasculaire Translationnelle (LVTS (UMR_S_1148 / U1148)), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité)-Université Sorbonne Paris Nord, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Grenier, Jérôme, Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP)-Université Sorbonne Paris Nord, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Univ Paris Diderot, INSERM, Lab Vasc Translat Sci U1148, Paris, France |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
MESH: 3T3 Cells
Polymers [SDV]Life Sciences [q-bio] MESH: Freeze Drying Nucleation Biocompatible Materials MESH: Solvents 02 engineering and technology Biochemistry MESH: Tissue Engineering Mice Tissue engineering MESH: Biocompatible Materials Freezing MESH: Tissue Scaffolds MESH: Animals chemistry.chemical_classification 3D cell culture Aqueous solution Tissue Scaffolds Hydrogels General Medicine Polymer 3T3 Cells MESH: Bone and Bones 021001 nanoscience & nanotechnology Grain size MESH: Polymers Cross-Linking Reagents Self-healing hydrogels 0210 nano-technology Rheology Porosity Polysaccharide-based hydrogel Biotechnology MESH: Hydrogels [CHIM.POLY] Chemical Sciences/Polymers Materials science MESH: Microscopy Electron Scanning [SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering Polysaccharide-based MESH: Cross-Linking Reagents 0206 medical engineering Biomedical Engineering Porous scaffolds Bone and Bones Biomaterials MESH: Porosity Polysaccharides MESH: Rheology Animals [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering [SDV.IB.BIO]Life Sciences [q-bio]/Bioengineering/Biomaterials Molecular Biology Ice-templating MESH: Mice Tissue Engineering technology industry and agriculture 020601 biomedical engineering [SDV.IB.BIO] Life Sciences [q-bio]/Bioengineering/Biomaterials Hydrogel Freeze Drying MESH: Polysaccharides [CHIM.POLY]Chemical Sciences/Polymers Chemical engineering chemistry Ionic strength Freeze-drying Microscopy Electron Scanning Solvents MESH: Freezing |
| Zdroj: | Acta Biomaterialia Acta Biomaterialia, 2019, 94, pp.195-203. ⟨10.1016/j.actbio.2019.05.070⟩ Acta Biomaterialia, Elsevier, 2019, 94, pp.195-203. ⟨10.1016/j.actbio.2019.05.070⟩ |
| ISSN: | 1742-7061 |
| DOI: | 10.1016/j.actbio.2019.05.070⟩ |
| Popis: | Whereas freeze-drying is a widely used method to produce porous hydrogel scaffolds, the mechanisms of pore formation involved in this process remained poorly characterized. To explore this, we focused on a cross-linked polysaccharide-based hydrogel developed for bone tissue engineering. Scaffolds were first swollen in 0.025% NaCl then freeze-dried at low cooling rate, i.e. −0.1 °C min−1, and finally swollen in aqueous solvents of increasing ionic strength. We found that scaffold’s porous structure is strongly conditioned by the nucleation of ice. Electron cryo-microscopy of frozen scaffolds demonstrates that each pore results from the growth of one to a few ice grains. Most crystals were formed by secondary nucleation since very few nucleating sites were initially present in each scaffold (0.1 nuclei cm−3 °C−1). The polymer chains are rejected in the intergranular space and form a macro-network. Its characteristic length scale coincides with the ice grain size (160 μ m ) and is several orders of magnitude greater than the mesh size (90 nm) of the cross-linked network. After sublimation, the ice grains are replaced by macro-pores of 280 μ m mean size and the resulting dry structure is highly porous, i.e. 93%, as measured by high-resolution X-ray tomography. In the swollen state, the scaffold mean pore size decreases in aqueous solvent of increasing ionic strength (120 µm in 0.025% NaCl and 54 µm in DBPS) but the porosity remains the same, i.e. 29% regardless of the solvent. Finally, cell seeding of dried scaffolds demonstrates that the pores are adequately interconnected to allow homogenous cell distribution. Statement of Significance The fabrication of hydrogel scaffolds is an important research area in tissue engineering. Hydrogels are textured to provide a 3D-framework that is favorable for cell proliferation and/or differentiation. Optimum hydrogel pore size depends on its biological application. Producing porous hydrogels is commonly achieved through freeze-drying. However, the mechanisms of pore formation remain to be fully understood. We carefully analyzed scaffolds of a cross-linked polysaccharide-based hydrogel developed for bone tissue engineering, using state-of-the-art microscopic techniques. Our experimental results evidenced the shaping of hydrogel during the freezing step, through a specific ice-templating mechanism. These findings will guide the strategies for controlling the porous structure of hydrogel scaffolds. |
| Databáze: | OpenAIRE |
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