Effects of Charge on Osmotic Reflection Coefficients of Macromolecules in Fibrous Membranes
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Bhalla-2009-Effects of Charge on.pdf
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Author(s)
Bhalla, Gaurav
Deen, William M.
Date Issued
September 2009
Journal
Biophysical Journal
Publisher
Elsevier
Citation
Bhalla, Gaurav, and William M. Deen. “Effects of Charge on Osmotic Reflection Coefficients of Macromolecules in Fibrous Membranes.” Biophysical Journal 97, no. 6 (September 2009): 1595–1605. © 2009 Biophysical Society.
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Final published version
Abstract
A model based on continuum hydrodynamics and electrostatics was developed to predict the combined effects of molecular charge and size on the osmotic reflection coefficient (σ[subscript o]) of a macromolecule in a fibrous membrane, such as a biological hydrogel. The macromolecule was represented as a sphere with a constant surface charge density, and the membrane was assumed to consist of an array of parallel fibers of like charge, also with a constant surface charge density. The flow was assumed to be parallel to the fiber axes. The effects of charge were included by computing the electrostatic free energy for a sphere interacting with an array of fibers. It was shown that this energy could be approximated using a pairwise additivity assumption. Results for σ[subscript o] were obtained for two types of negatively charged fibers, one with properties like those of glycosaminoglycan chains, and the other for thicker fibers having a range of charge densities. Using physiologically reasonable fiber spacings and charge densities, σ[subscript o] for bovine serum albumin in either type of fiber array was shown to be much larger than that for an uncharged system. Given the close correspondence between σ[subscript o] and the reflection coefficient for filtration, the results suggest that the negative charge of structures such as the endothelial surface glycocalyx is important in minimizing albumin loss from the circulation.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
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DOI of Published Version
https://doi.org/10.1016/j.bpj.2009.06.038
