title: Study of uremic toxin fluxes across nanofabricated hemodialysis membranes using irreversible thermodynamics.
abstract: BACKGROUND
  The flux of uremic toxin middle molecules through currently used hemodialysis membranes is suboptimal, mainly because of the membranes' pore architecture.
  
  
  OBJECTIVE
  Identifying the modifiable sieving parameters that can be improved by nanotechnology to enhance fluxes of uremic toxins across the walls of dialyzers' capillaries.
  
  
  METHODS
  We determined the maximal dimensions of endothelin, cystatin C, and interleukin - 6 using the macromolecular modeling software, COOT. We also applied the expanded Nernst-Plank equation to calculate the changes in the overall flux as a function of increased electro-migration and pH of the respective molecules.
  
  
  RESULTS
  In a high flux hemodialyzer, the effective diffusivities of endothelin, cystatin C, and interleukin - 6 are 15.00 x 10(-10) cm(2)/s, 7.7 x 10(-10) cm(2)/s, and 5.4 x 10(-10) cm(2)/s, respectively, through the capillaries' walls. In a nanofabricated membrane, the effective diffusivities of endothelin, cystatin C, and interleukin - 6 are 13.87 x 10(-7) cm(2)/s, 5.73 x 10(-7) cm(2)/s, and 3.45 x 10(-7) cm(2)/s, respectively, through a nanofabricated membrane. Theoretical modeling showed that a 96% reduction in the membrane's thickness and the application of an electric potential of 10 mV across the membrane could enhance the flux of endothelin, cystatin C, and interleukin - 6 by a factor of 25. A ΔpH of 0.07 altered the fluxes minimally.
  
  
  CONCLUSIONS
  Nanofabricated hemodialysis membranes with a reduced thickness and an applied electric potential can enhance the effective diffusivity and electro-migration flux of the respective uremic toxins by 3 orders of magnitude as compared to those passing through the high flux hemodialyzer.
authors.affiliation: College of Dentistry, University of Saskatchewan, 105 Wiggins Road, Saskatoon, SK, S7N 5E4, Canada.
authors.forename: Assem
authors.initials: A
authors.lastname: Hedayat
authors.affiliation: Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9, Canada.
authors.forename: Rob
authors.initials: R
authors.lastname: Peace
authors.affiliation: Saskatchewan Transplant Program, St. Paul's Hospital, 1702, 20th Street West, Saskatoon, SK, S7M 0Z9, Canada.
authors.forename: Hamdi
authors.initials: H
authors.lastname: Elmoselhi
authors.affiliation: Saskatchewan Transplant Program, St. Paul's Hospital, 1702, 20th Street West, Saskatoon, SK, S7M 0Z9, Canada ; Division of Nephrology, Department of Medicine, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK, S7N 0W8, Canada.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Shoker
keywords: cystatin C; endothelin; hemodialysis membranes; interleukin-6; nanofabrication; uremic toxins