Values and property charts for anisotropic freeze-cast collagen scaffolds for tissue regeneration

Divakar, Prajan; Yin, Kaiyang; Wegst, Ulrike G. K.

doi:10.1016/j.dib.2018.10.171

Cited by 7 publications

(2 citation statements)

References 8 publications

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“…As the dependence on both the freezing rate and slurry composition indicates, ridges are favored, when the solutes/particles are well dispersed and no fibrillation can occur in the material system. Bridges result from fibril and fiber trapping in the increasingly viscous polymer solution during the solidification process, ,,− while the majority of CNFs remain homogeneously dispersed to form slightly textured film-like cell walls, as earlier observed in the freeze-cast scaffolds composed only of CNFs (Figure B) …”

Section: Resultsmentioning

confidence: 64%

Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

2019

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Despite considerable recent interest in microand nanofibrillated cellulose as constituents of lightweight structures and scaffolds for applications that range from thermal insulation to filtration, few systematic studies have been reported to date on structure−property-processing correlations in freeze-cast chitosan−nanocellulose composite scaffolds, in general, and their application in tissue regeneration, in particular. Reported in this study are the effects of the addition of plant-derived nanocellulose fibrils (CNF), crystals (CNCs), or a blend of the two (CNB) to the biopolymer chitosan on the structure and properties of the resulting composites. Chitosan−nanocellulose composite scaffolds were freeze-cast at 10 and 1 °C/min, and their microstructures were quantified in both the dry and fully hydrated states using scanning electron and confocal microscopy, respectively. The modulus, yield strength, and toughness (work to 60% strain) were determined in compression parallel and the modulus also perpendicular to the freezing direction to quantify anisotropy. Observed were the preferential alignments of CNCs and/or fibrils parallel to the freezing direction. Additionally, observed was the self-assembly of the nanocellulose into microstruts and microbridges between adjacent cell walls (lamellae), features that affected the mechanical properties of the scaffolds. When freeze-cast at 1 °C/min, chitosan−CNF scaffolds had the highest modulus, yield strength, toughness, and smallest anisotropy ratio, followed by chitosan and the composites made with the nanocellulose blend, and that with crystalline cellulose. These results illustrate that the nanocellulose additions homogenize the mechanical properties of the scaffold through cell-wall material self-assembly, on the one hand, and add architectural features such as bridges and pillars, on the other. The latter transfer loads and enable the scaffolds to resist deformation also perpendicular to the freezing direction. The observed property profile and the materials' proven biocompatibility highlight the promise of chitosan−nanocellulose composites for a large range of applications, including those for biomedical implants and devices.

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Section: Resultsmentioning

confidence: 64%

Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

2019

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“…Scaffold structure, mechanical properties, and degradation rate can be custom-designed through material composition, processing parameters (e.g. the freezing rate), and the degree of crosslinking [5,6,10,[12][13][14][15][16][17][18]. In addition to a robust architecture, freeze-cast biopolymer scaffolds offer attractive mechanical and chemical cues that invite cell and tissue integration in vivo with minimal inflammatory and fibrotic responses; additionally, they have desirable biodegradation and bioresorbability profiles [19,20].…”

Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of the in vivo biocompatibility and performance of freeze-cast tissue scaffolds

Divakar¹,

Moodie²,

Demidenko³

et al. 2020

Biomed. Mater.

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Quantitative methods are little used for the in vivo assessment of tissue scaffolds to evaluate biocompatibility. To complement current histological techniques, we introduce as a measure of biocompatibility a straightforward, geometric analysis for the quantitative assessment of encapsulation thickness, cross-sectional area, and biomaterial shape. Advantages of this new technique are that it enables, on the one hand, a more complete and objective comparison of scaffolds with differing compositions, architectures, and mechanical properties, and, on the other, a more objective approach to their selection for a given application. In this contribution, we focus on freeze-cast polymeric scaffolds for tissue regeneration and their subcutaneous implantation in mice for biocompatibility testing. Initially, seven different scaffold types are screened. Of these, three are selected for systematic biocompatibility studies based on histopathological criteria: EDC-NHS-crosslinked bovine collagen, EDC-NHS-crosslinked bovine collagen-nanocellulose, and chitin. Geometric models developed to quantify scaffold size, ovalization, and encapsulation thickness are tested, evaluated, and found to be a powerful and objective metric for the in vivo assessment of biocompatibility and performance of tissue scaffolds.

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X‐Ray Tomoscopy Reveals the Dynamics of Ice Templating

Kamm,

Yin,

Neu

et al. 2023

Adv Funct Materials

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Little experimentally explored and understood are the complex dynamics of microstructure formation by ice‐templating when aqueous solutions or slurries are directionally solidified (freeze cast) into cellular solids. With synchrotron‐based, time‐resolved X‐ray tomoscopy it is possible to study in situ under well‐defined conditions the anisotropic, partially faceted growth of ice crystals in aqueous systems. Obtaining one full tomogram per second for ≈270 s with a spatial resolution of 6 µm, it is possible to capture with minimal X‐ray absorption, the freezing front in a 3% weight/volume (w/v) sucrose‐in‐water solution, which typically progresses at 5–30 µm s−1 for applied cooling rates of = 1–10 °C min−1. These time and length scales render X‐ray tomoscopy ideally suited to quantify in 3D ice crystal growth and templating phenomena that determine the performance‐defining hierarchical architecture of freeze‐cast materials: a complex pore morphology and “ridges”, “jellyfish cap”, and “tentacle”‐like secondary features, which decorate the cell walls.

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Values and property charts for anisotropic freeze-cast collagen scaffolds for tissue regeneration

Cited by 7 publications

References 8 publications

Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

Quantitative evaluation of the in vivo biocompatibility and performance of freeze-cast tissue scaffolds

X‐Ray Tomoscopy Reveals the Dynamics of Ice Templating

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