A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY
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| Language: | English |
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Cleveland State University / OhioLINK
2013
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=csu1369858556 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-csu1369858556 |
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oai_dc |
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NDLTD |
| language |
English |
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NDLTD |
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Biomedical Engineering |
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Biomedical Engineering Sawonik, Michael A. A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| author |
Sawonik, Michael A. |
| author_facet |
Sawonik, Michael A. |
| author_sort |
Sawonik, Michael A. |
| title |
A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| title_short |
A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| title_full |
A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| title_fullStr |
A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| title_full_unstemmed |
A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY |
| title_sort |
microfluidic platform to quantify spatio-temporal diffusion of chemo-gradients within 3d scaffolds: applications in axonal biology |
| publisher |
Cleveland State University / OhioLINK |
| publishDate |
2013 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=csu1369858556 |
| work_keys_str_mv |
AT sawonikmichaela amicrofluidicplatformtoquantifyspatiotemporaldiffusionofchemogradientswithin3dscaffoldsapplicationsinaxonalbiology AT sawonikmichaela microfluidicplatformtoquantifyspatiotemporaldiffusionofchemogradientswithin3dscaffoldsapplicationsinaxonalbiology |
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1719419727397257216 |
| spelling |
ndltd-OhioLink-oai-etd.ohiolink.edu-csu13698585562021-08-03T05:23:42Z A MICROFLUIDIC PLATFORM TO QUANTIFY SPATIO-TEMPORAL DIFFUSION OF CHEMO-GRADIENTS WITHIN 3D SCAFFOLDS: APPLICATIONS IN AXONAL BIOLOGY Sawonik, Michael A. Biomedical Engineering Axonal outgrowth and guidance play an important role in wiring the developing and regenerating nervous system. The critical role of biomolecular gradients in facilitating this axonal sensitivity and directionality along specific trajectories needs to be elucidated for designing effective therapeutic treatments under injury or disease conditions. However, previous in vitro approaches based on micropipette assay or gel-turning assay proved to be unsuitable or inefficient for precise generation and quantification of diffusive gradients. In this study, we utilized a microfluidic device to generate and quantify physiologically-relevant biomolecular gradients in a simple and reliable manner. Using a combination of computational and experimental techniques, we designed and developed a microfluidic platform to study the synergistic effects of 3D scaffold concentration (0 - 3 mg/mL), molecular weight of the diffusing molecule (1-1000 kDa) as well as its dosage (0.1-10 µM), on gradient generation and steady-state spatio-temporal evolution. The device was fabricated using standard soft-lithography techniques, and has three separate chambers, flanked by two media channels on the sides. The scaffold (gel) of interest was filled in the left and right chambers (L = 3.6 mm, thickness = 150 µm), and the biomolecule of interest was loaded in the middle chamber to facilitate diffusion through the gel on both sides. The channels on both sides act as sink for the diffusing biomolecule, creating a gradient across the 3D gel. Two different types of scaffolding materials were used in these studies – collagen-1 or matrigel®. The viscosities of these gels at various concentrations were obtained from commercial vendors, and diffusion coefficients of biomolecules within these gels calculated using the Stokes-Einstein equation. Computational simulations were performed using the finite element methods (COMSOL® Multiphysics), to obtain a gradient profile across the chamber in all three dimensions. The numerical grid for performing the simulations consisted of approximately 250,000 triangular elements for the 2D simulations and tetrahedral elements for the 3D simulations. Primary rat cortical neurons were cultured within 3D 2 mg/mL collagen-1 gel within these devices and exposed to a gradient of 10 ¿g/mL IGF-1 for 48 h. The neurite outgrowth and turning towards the chemogradient was imaged and quantified, and correlated to the gradient concentrations and steepness at various locations within the device.Results showed that steady-state diffusion times are strongly dependent on gel concentration and molecular weight of diffusing molecule. For example, while the steady-state condition was reached in 2 h for 1 kDa Dextran diffusing in 1 mg/mL collagen, it took more than 125 h for the 1000 kDa molecule to diffuse in 3 mg/mL collagen. However, the initial concentration of diffusing molecule (0.1-10 µM) appeared to have no significant effect on attainment of steady-state time under these conditions. Molecular diffusion did not exhibit any variation along y and z-axes within the device, and progressed only along x-axis across the chamber. A generalized equation for the time needed to reach steady-state was proposed, based on scaffold concentration and the molecular weight of the diffusing molecule. The steepness of the gradient at different regions of 3D gel was found to be 1% or less across a 10 µm cross-section, taken at 6 locations across the chamber. Axonal outgrowth and turning was significantly affected by the IGF-I gradient. At the higher IGF-I concentrations in the device, average outgrowth increased to 92 µm compared to only 17 µm in the control samples while the majority of neurites (53%) turned towards the gradient. In conclusion, the device investigated appears to be capable of generating stable chemical gradients across its chambers for the study of axonal regeneration as well as other biological problems where chemogradients play a major role. 2013-06-05 English text Cleveland State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=csu1369858556 http://rave.ohiolink.edu/etdc/view?acc_num=csu1369858556 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |