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Size-Dependent Diffusion of Dextrans in Excised Porcine Corneal Stroma

Ajith Rajapaksha1,2, Michael Fink1, Brian A. Todd1

Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
Corresponding author E-mail: ajith@purdue.edu

Molecular & Cellular Biomechanics 2015, 12(3), 215-230. https://doi.org/10.3970/mcb.2015.012.215


Delivery of therapeutic agents to the eye requires efficient transport through cellular and extracellular barriers. We evaluated the rate of diffusive transport in excised porcine corneal stroma using fluorescently labeled dextran molecules with hydrodynamic radii ranging from 1.3 to 34 nm. Fluorescence correlation spectroscopy (FCS) was used to measure diffusion coefficients of dextran molecules in the excised porcine corneal stroma. The preferential sensitivity of FCS to diffusion along two dimensions was used to differentially probe diffusion along the directions parallel to and perpendicular to the collagen lamellae of the corneal stroma. In order to develop an understanding of how size affects diffusion in cornea, diffusion coefficients in cornea were compared to diffusion coefficients measured in a simple buffer solution. Dextran molecules diffuse more slowly in cornea as compared to buffer solution. The reduction in diffusion coefficient is modest however (67% smaller), and is uniform over the range of sizes that we measured. This indicates that, for dextrans in the 1.3 to 34 nm range, the diffusion landscape of corneal stroma can be represented as a simple liquid with a viscosity approximately 1.5 times that of water. Diffusion coefficients measured parallel vs. perpendicular to the collagen lamellae were indistinguishable. This indicates that diffusion in the corneal stroma is not highly anisotropic. Our results support the notion that the corneal stroma is highly permeable and isotropic to transport of hydrophilic molecules and particles with hydrodynamic radii up to at least 34 nm.


Cite This Article

APA Style
Rajapaksha, A., Fink, M., Todd, B.A. (2015). Size-dependent diffusion of dextrans in excised porcine corneal stroma. Molecular & Cellular Biomechanics, 12(3), 215-230. https://doi.org/10.3970/mcb.2015.012.215
Vancouver Style
Rajapaksha A, Fink M, Todd BA. Size-dependent diffusion of dextrans in excised porcine corneal stroma. Mol Cellular Biomechanics . 2015;12(3):215-230 https://doi.org/10.3970/mcb.2015.012.215
IEEE Style
A. Rajapaksha, M. Fink, and B.A. Todd "Size-Dependent Diffusion of Dextrans in Excised Porcine Corneal Stroma," Mol. Cellular Biomechanics , vol. 12, no. 3, pp. 215-230. 2015. https://doi.org/10.3970/mcb.2015.012.215

cc This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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