The Experts below are selected from a list of 18405 Experts worldwide ranked by ideXlab platform
Michael J. Yaszemski - One of the best experts on this subject based on the ideXlab platform.
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three dimensional porous biodegradable polymeric scaffolds fabricated with biodegradable hydrogel porogens
Tissue Engineering Part C-methods, 2009Co-Authors: Jinku Kim, Michael J. Yaszemski, Lichun LuAbstract:We have developed a new fabrication technique to create three-dimensional (3D) porous poly(e-caprolactone fumarate) (PCLF) scaffolds using hydrogel microparticle porogens, as an alternative to overcome certain limitations of traditional scaffold fabrication techniques such as a salt leaching method. Both natural hydrogel, gelatin, and synthetic hydrogel, poly(ethylene glycol) sebacic acid diacrylate, were used as porogens to fabricate 3D porous PCLF scaffolds. Hydrogel microparticles were prepared by a single emulsion technique with the particle size in the range of 100–500 μm after equilibrium in water. The pore size distribution, porosity, pore Interconnectivity, and spatial pore heterogeneity of the 3D PCLF scaffolds were assessed using micro-computed tomography and imaging analysis. Scaffolds fabricated with the hydrogel porogens had higher porosity and pore Interconnectivity as well as more homogeneous spatial pore distribution, compared to the scaffolds made from the salt leaching process. Compressi...
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quantitative analysis of Interconnectivity of porous biodegradable scaffolds with micro computed tomography
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Michael J Moore, Esmaiel Jabbari, Erik L Ritman, Bradford L Currier, Anthony J Windebank, Michael J. YaszemskiAbstract:Pore Interconnectivity within scaffolds is an important parameter influencing cell migration and tissue ingrowth needed to promote tissue regeneration. Methods for assessment of Interconnectivity are usually qualitative, restricted to two-dimensional images, or are destructive. Microcomputed tomography nondestructively provides three-dimensional (3D) images of intact specimens at high spatial resolutions. We describe an image analysis technique for quantitative assessment of scaffold Interconnectivity. Scaffolds were made via a particulate leaching process with 75%, 80%, 85%, and 88% volumetric porogen fractions. Specimens were scanned and resulting 3D, digital images were analyzed with a custom algorithm. A series of virtual, idealized scaffolds were also created for illustration of the algorithm's analysis approach and for its validation. The program calculated accessible void fractions over a range of minimum connection sizes. In real specimens, nearly 100% of the porous volume was connected with outside air for connections greater than or equal to 20 microm in their smallest dimension. In scaffolds made with 75% porogen, the accessible void fraction decreased to 78% if only those connections greater than or equal to 260 microm were considered. The relationship between accessible void fraction and connection size varied as a function of porogen content. The Interconnectivity parameter described here may have implications for cell migration and tissue growth into scaffolds.
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quantitative analysis of Interconnectivity of porous biodegradable scaffolds with micro computed tomography
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Michael J Moore, Lichun Lu, Esmaiel Jabbari, Erik L Ritman, Bradford L Currier, Anthony J Windebank, Michael J. YaszemskiAbstract:Pore Interconnectivity within scaffolds is an im- portant parameter influencing cell migration and tissue in- growth needed to promote tissue regeneration. Methods for assessment of Interconnectivity are usually qualitative, re- stricted to two-dimensional images, or are destructive. Mi- crocomputed tomography nondestructively provides three- dimensional (3D) images of intact specimens at high spatial resolutions. We describe an image analysis technique for quantitative assessment of scaffold Interconnectivity. Scaf- folds were made via a particulate leaching process with 75%, 80%, 85%, and 88% volumetric porogen fractions. Specimens were scanned and resulting 3D, digital images were ana- lyzed with a custom algorithm. A series of virtual, idealized scaffolds were also created for illustration of the algorithm's analysis approach and for its validation. The program cal- culated accessible void fractions over a range of minimum connection sizes. In real specimens, nearly 100% of the po- rous volume was connected with outside air for connections greater than or equal to 20 m in their smallest dimension. In scaffolds made with 75% porogen, the accessible void fraction decreased to 78% if only those connections greater than or equal to 260 m were considered. The relationship between accessible void fraction and connection size varied as a function of porogen content. The Interconnectivity pa- rameter described here may have implications for cell mi- gration and tissue growth into scaffolds. © 2004 Wiley Pe- riodicals, Inc. J Biomed Mater Res 71A: 258 -267, 2004
Arend Jan Schouten - One of the best experts on this subject based on the ideXlab platform.
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polyurethane scaffold formation via a combination of salt leaching and thermally induced phase separation
Journal of Biomedical Materials Research Part A, 2008Co-Authors: R. G. J. C. Heijkants, Pieter Buma, R.v. Van Calck, J.h. De Groot, Aj Pennings, T.g. Van Tienen, R P H Veth, Arend Jan SchoutenAbstract:Porous scaffolds have been made from two polyurethanes based on thermally induced phase separation of polymer dissolved in a DMSO/water mixture in combination with salt leaching. It is possible to obtain very porous foams with a very high Interconnectivity. A major advantage of this method is that variables like porosity, pore size, and Interconnectivity can be independently adjusted with the absence of toxic materials in the production process. The obtained compression moduli were between 200 kPa and 1 MPa with a variation in porosity between 76 and 84%. Currently the biological and medical aspects are under evaluation.
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preparation of a polyurethane scaffold for tissue engineering made by a combination of salt leaching and freeze drying of dioxane
Journal of Materials Science, 2006Co-Authors: R. G. J. C. Heijkants, Pieter Buma, J.h. De Groot, Aj Pennings, T.g. Van Tienen, R P H Veth, Arend Jan SchoutenAbstract:In the past several types of synthetic porous materials have been made as meniscus reconstruction materials. Most of these materials lacked a good combination between suitable mechanical properties and a high Interconnectivity. In this work porous scaffolds were made from the polyurethane Estane 5701-F1 by freeze drying of a dioxane and water solution in combination with salt leaching. It was possible to obtain very porous scaffolds with a very high Interconnectivity. Porosity, pore size and Interconnectivity can be independently adjusted by varying the amount of water, porogen size and the amount of porogen used. The obtained compression moduli of the scaffolds were between 40 kPa and 400 kPa with a variation in porosity between 72 and 87%. These scaffolds are very suitable for the use as meniscus replacement materials.
Lichun Lu - One of the best experts on this subject based on the ideXlab platform.
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three dimensional porous biodegradable polymeric scaffolds fabricated with biodegradable hydrogel porogens
Tissue Engineering Part C-methods, 2009Co-Authors: Jinku Kim, Michael J. Yaszemski, Lichun LuAbstract:We have developed a new fabrication technique to create three-dimensional (3D) porous poly(e-caprolactone fumarate) (PCLF) scaffolds using hydrogel microparticle porogens, as an alternative to overcome certain limitations of traditional scaffold fabrication techniques such as a salt leaching method. Both natural hydrogel, gelatin, and synthetic hydrogel, poly(ethylene glycol) sebacic acid diacrylate, were used as porogens to fabricate 3D porous PCLF scaffolds. Hydrogel microparticles were prepared by a single emulsion technique with the particle size in the range of 100–500 μm after equilibrium in water. The pore size distribution, porosity, pore Interconnectivity, and spatial pore heterogeneity of the 3D PCLF scaffolds were assessed using micro-computed tomography and imaging analysis. Scaffolds fabricated with the hydrogel porogens had higher porosity and pore Interconnectivity as well as more homogeneous spatial pore distribution, compared to the scaffolds made from the salt leaching process. Compressi...
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quantitative analysis of Interconnectivity of porous biodegradable scaffolds with micro computed tomography
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Michael J Moore, Lichun Lu, Esmaiel Jabbari, Erik L Ritman, Bradford L Currier, Anthony J Windebank, Michael J. YaszemskiAbstract:Pore Interconnectivity within scaffolds is an im- portant parameter influencing cell migration and tissue in- growth needed to promote tissue regeneration. Methods for assessment of Interconnectivity are usually qualitative, re- stricted to two-dimensional images, or are destructive. Mi- crocomputed tomography nondestructively provides three- dimensional (3D) images of intact specimens at high spatial resolutions. We describe an image analysis technique for quantitative assessment of scaffold Interconnectivity. Scaf- folds were made via a particulate leaching process with 75%, 80%, 85%, and 88% volumetric porogen fractions. Specimens were scanned and resulting 3D, digital images were ana- lyzed with a custom algorithm. A series of virtual, idealized scaffolds were also created for illustration of the algorithm's analysis approach and for its validation. The program cal- culated accessible void fractions over a range of minimum connection sizes. In real specimens, nearly 100% of the po- rous volume was connected with outside air for connections greater than or equal to 20 m in their smallest dimension. In scaffolds made with 75% porogen, the accessible void fraction decreased to 78% if only those connections greater than or equal to 260 m were considered. The relationship between accessible void fraction and connection size varied as a function of porogen content. The Interconnectivity pa- rameter described here may have implications for cell mi- gration and tissue growth into scaffolds. © 2004 Wiley Pe- riodicals, Inc. J Biomed Mater Res 71A: 258 -267, 2004
Gregory J Exarhos - One of the best experts on this subject based on the ideXlab platform.
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probing porosity and pore Interconnectivity in self assembled tio2 graphene hybrid nanostructures using hyperpolarized 129xe nmr
Journal of Physical Chemistry C, 2012Co-Authors: Liqiong Wang, Donghai Wang, Jun Liu, Gregory J ExarhosAbstract:Hyperpolarized (HP) 129Xe NMR was used to probe the porosity and Interconnectivity of pores in self-assembled hybrid TiO2–graphene nanostructures. We have demonstrated that HP 129Xe NMR is a powerful technique in probing any changes in porosity and Interconnectivity of the pores caused by the addition of a small amount of functionalized graphene sheets (FGSs) (1% weight percent) into the network of mesoporous TiO2. To obtain the information on the changes in porosity and Interconnectivity of the pores caused by the addition of a small amount of FGSs, a comparative study has been carried out by acquiring HP 129Xe NMR spectra under identical experimental conditions for both pure mesoporous TiO2 and hybrid TiO2–FGSs. The HP 129Xe NMR results from our comparative study suggest that TiO2 and graphene are mixed uniformly on the nanoscale and the resulting hybrid nanostructure has better channel connectivity between different domains, enhancing the transport property for Li-insertion/extraction.
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probing porosity and pore Interconnectivity in crystalline mesoporous tio2 using hyperpolarized 129xe nmr
Journal of Physical Chemistry C, 2009Co-Authors: Liqiong Wang, Donghai Wang, Jun Liu, Gregory J Exarhos, Shane Pawsey, Igor L MoudrakovskiAbstract:Hyperpolarized (HP) 129Xe NMR was used to probe the porosity and Interconnectivity of pores in crystalline mesoporous TiO2. We have demonstrated that HP 129Xe NMR can be used to differentiate between similar sized pores within different crystalline phases. Pores of 4 nm size resident in mixed anatase and rutile mesoporous TiO2 phases were identified. Complementary to other pore characterization techniques, HP 129Xe NMR is able to probe the Interconnectivity between pores present in these different phases. The cross peaks in 2D exchange (EXSY) NMR spectra between the signals of xenon in two types of pores are visible on millisecond timescale, indicating substantial pore Interconnectivity. The obtained information on porosity and Interconnectivity is important for the understanding of ion transport mechanisms in mesoporous TiO2 anode materials.
Liqiong Wang - One of the best experts on this subject based on the ideXlab platform.
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probing porosity and pore Interconnectivity in self assembled tio2 graphene hybrid nanostructures using hyperpolarized 129xe nmr
Journal of Physical Chemistry C, 2012Co-Authors: Liqiong Wang, Donghai Wang, Jun Liu, Gregory J ExarhosAbstract:Hyperpolarized (HP) 129Xe NMR was used to probe the porosity and Interconnectivity of pores in self-assembled hybrid TiO2–graphene nanostructures. We have demonstrated that HP 129Xe NMR is a powerful technique in probing any changes in porosity and Interconnectivity of the pores caused by the addition of a small amount of functionalized graphene sheets (FGSs) (1% weight percent) into the network of mesoporous TiO2. To obtain the information on the changes in porosity and Interconnectivity of the pores caused by the addition of a small amount of FGSs, a comparative study has been carried out by acquiring HP 129Xe NMR spectra under identical experimental conditions for both pure mesoporous TiO2 and hybrid TiO2–FGSs. The HP 129Xe NMR results from our comparative study suggest that TiO2 and graphene are mixed uniformly on the nanoscale and the resulting hybrid nanostructure has better channel connectivity between different domains, enhancing the transport property for Li-insertion/extraction.
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probing porosity and pore Interconnectivity in crystalline mesoporous tio2 using hyperpolarized 129xe nmr
Journal of Physical Chemistry C, 2009Co-Authors: Liqiong Wang, Donghai Wang, Jun Liu, Gregory J Exarhos, Shane Pawsey, Igor L MoudrakovskiAbstract:Hyperpolarized (HP) 129Xe NMR was used to probe the porosity and Interconnectivity of pores in crystalline mesoporous TiO2. We have demonstrated that HP 129Xe NMR can be used to differentiate between similar sized pores within different crystalline phases. Pores of 4 nm size resident in mixed anatase and rutile mesoporous TiO2 phases were identified. Complementary to other pore characterization techniques, HP 129Xe NMR is able to probe the Interconnectivity between pores present in these different phases. The cross peaks in 2D exchange (EXSY) NMR spectra between the signals of xenon in two types of pores are visible on millisecond timescale, indicating substantial pore Interconnectivity. The obtained information on porosity and Interconnectivity is important for the understanding of ion transport mechanisms in mesoporous TiO2 anode materials.
