Understanding anisotropy and architecture in ice-templated biopolymer scaffolds

Pawelec, Kendell M.; Husmann, Anke; Best, Serena M.; Cameron, Ruth E.

doi:10.1016/j.msec.2014.01.009

Cited by 93 publications

(91 citation statements)

References 31 publications

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“…It has already been observed that the nucleation temperature has a huge impact on scaffold structure, as it is chiefly responsible for whether scaffolds are isotropic or anisotropic [5,7]. However, this study found no correlation between nucleation temperature and the final pore size at the top of the scaffold.…”

Section: Relationship Between Pore Structure and Thermal Parameterscontrasting

confidence: 77%

“…As the goal of this study was to link the pore size of isotropic scaffolds to a single thermal parameter, regardless of processing conditions, data were pooled from a previous study to evaluate the fit of the curve [7,17]. It was found that of all the thermal parameters tested, the time at equilibrium had the strongest relationship to pore size (figure 7).…”

Section: Relating Scaffold Architecture To Thermal Parametersmentioning

confidence: 99%

“…Inset: the slope of the curve was 1/n, where n ¼ 4.8; fit with a linear regression curve ( p , 0.05, R 2 ¼ 0.8). Closed markers, measurements at the top of slurry; open markers, base of slurry; colours correspond to filling height of the slurry and the shape of the symbols marks the set freezing conditions [7,17]. (Online version in colour.…”

Section: Defining Time At Equilibriummentioning

confidence: 99%

“…It has been shown previously that the nucleation step controls the anisotropy of the scaffold structure [7]. If a region of slurry has not yet reached the equilibrium freezing temperature when primary nucleation occurs, a condition that can be created through slurry filling height and mould design, an anisotropic scaffold results [17].…”

Section: Design Protocol For Tailoring Ice-templated Scaffold Structurementioning

confidence: 99%

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A design protocol for tailoring ice-templated scaffold structure

Pawelec

Husmann

Best

et al. 2014

J. R. Soc. Interface.

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ResearchCite this article: Pawelec KM, Husmann A, Best SM, Cameron RE. 2014 A design protocol for tailoring ice-templated scaffold structure. J. R. Soc. In this paper, we show, for the first time, the key link between scaffold architecture and latent heat evolution during the production of porous biomedical collagen structures using freeze-drying. Collagen scaffolds are used widely in the biomedical industry for the repair and reconstruction of skeletal tissues and organs. Freeze-drying of collagen slurries is a standard industrial process, and, until now, the literature has sought to characterize the influence of set processing parameters including the freezing protocol and weight percentage of collagen. However, we are able to demonstrate, by monitoring the local thermal events within the slurry during solidification, that nucleation, growth and annealing processes can be controlled, and therefore we are able to control the resulting scaffold architecture. Based on our correlation of thermal profile measurements with scaffold architecture, we hypothesize that there is a link between the fundamental freezing of ice and the structure of scaffolds, which suggests that this concept is applicable not only for collagen but also for ceramics and pharmaceuticals. We present a design protocol of strategies for tailoring the ice-templated scaffold structure.

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Section: Relationship Between Pore Structure and Thermal Parameterscontrasting

confidence: 77%

Section: Relating Scaffold Architecture To Thermal Parametersmentioning

confidence: 99%

Section: Defining Time At Equilibriummentioning

confidence: 99%

Section: Design Protocol For Tailoring Ice-templated Scaffold Structurementioning

confidence: 99%

See 2 more Smart Citations

A design protocol for tailoring ice-templated scaffold structure

Pawelec

Husmann

Best

et al. 2014

J. R. Soc. Interface.

Self Cite

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show abstract

“…17 Some authors also use SEM images for observations of scaffold anisotropy, but these are rarely quantitative. 45,46 Alternatively, a three-dimensional (3D) set of images may be obtained by a tomographic technique: most commonly X-ray microcomputed tomography (micro-CT) or magnetic resonance imaging (MRI). These techniques can be advantageous because they are non-destructive and involve no sample deformation in preparation, and can be used to measure SAV, pore volume and connectivity parameters.…”

Section: Existing Characterisation Techniquesmentioning

confidence: 99%

Quantitative architectural description of tissue engineering scaffolds

Ashworth

Best

Cameron

2014

Materials Technology

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Arguably one of the most specialised subtopics in porous materials research is that of tissue engineering scaffolds. The porous architecture of these scaffolds is a key variable in determining biological response. However, techniques for characterising these materials tend to vary widely in the literature. There is a need for a set of transferable and effective methods for architectural characterisation. In this review, four key areas of importance are addressed. First, the definition and interpretation of pore size are considered in relation to fluid transport properties, by analogy with filtration research. Second, the definition of interconnectivity is discussed using insight obtained from cement and concrete research. Third, the issue of data scalability is addressed by consideration of percolation theory, as implemented for the study of geological materials. Finally, emerging techniques such as confocal and multiphoton microscopy are discussed. These methods allow the three-dimensional observation of pore strut arrangement, as well holding great potential for understanding changes in pore architecture under dynamic conditions.

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Towards Cellular Sieving: Exploring the Limits of Scaffold Accessibility for Cell Type Specific Invasion

et al. 2018

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of directing the regeneration of such complex tissues, a detailed understanding of the cell type dependent link between scaffold structure and cell motility is therefore required. In this work, we describe how this cell type dependence may be exploited toward cellular sieving: scaffold structures that permit differing degrees of invasion according to cell type. By comparing the invasion behavior of cells from three different sources, in scaffolds of systematically increasing accessibility, we probe the structural requirements for cell movement. In this way, we demonstrate that highly occlusive structures may be used to allow differential invasion according to cell type, therefore physically separating cells according to their invasive capacity.Freeze-dried collagen scaffolds are promising materials in the tissue engineering field, since their highly tunable structure and properties provide potential for the regeneration of a wide range of tissues. [5][6][7][8][9] In recent work, we have shown that measurement of pore size in these scaffolds is insufficient for predicting accessibility to cell invasion, and that characterizing the transport pathways through the pore space is also necessary. [10,11] These transport pathways can be characterized by measurement of percolation diameter, which describes the maximum object diameter that can move through a structure unimpeded. Percolation diameters below 40 µm have been shown to inhibit the invasion of primary fibroblasts, even in structures of constant pore size and collagen wall orientation. [11] In this study, we present simultaneous analysis of pore size and percolation diameter, meaning that, for the first time, we are able to compare their relative influences on the invasion potential of each cell type. The cells chosen for investigation reflect three distinct tissue engineering applications: human primary fibroblasts, for soft tissue regeneration; [12] the MC3T3 mouse osteoprogenitor cell line, for bone regeneration; [13] and the HT1080 cell line from human fibrosarcoma, reflecting the use of 3D models for studying tumor cell invasion. [14] As well as providing a tool for assaying the invasive capability of different cells in response to defined structures, this approach demonstrates how the informed design of tissue engineering scaffolds could be used to control the directed invasion of multiple cell types. The differing species, phenotype and origin of these cells is also relevant for demonstrating how the application of interest may determine the structural design criteria required for tissue engineering scaffolds, as well as the choice of cell line needed to provide an accurate biological assessment of such materials.Coordinating the behavior of multiple cell types provides a challenge for the tissue engineer, since response to structure is highly cell type dependent. Here, human primary fibroblast invasion is compared with that of the MC3T3 and HT1080 cell lines to demonstrate proof-of-concept that controlled changes in 3D collagen scaffold architecture can m...

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Understanding anisotropy and architecture in ice-templated biopolymer scaffolds

Cited by 93 publications

References 31 publications

A design protocol for tailoring ice-templated scaffold structure

A design protocol for tailoring ice-templated scaffold structure

Quantitative architectural description of tissue engineering scaffolds

Towards Cellular Sieving: Exploring the Limits of Scaffold Accessibility for Cell Type Specific Invasion

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