Kidney Week

Abstract: SA-PO418

Molecular Sieving via Conformational Flexing During Frictionless Flow in Slippery Carbon Nanotube Membranes for Hemodialysis

Session Information

• Hemodialysis and Frequent Dialysis: Clearance, Technology, Infection
  November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Kidambi, Piran, Vanderbilt University, Nashville, Tennessee, United States

Piran Kidambi,

• Cheng, Peifu, Vanderbilt University, Nashville, Tennessee, United States

Peifu Cheng,

• Ferrell, Nicholas J., The Ohio State University, Columbus, Ohio, United States

Nicholas J. Ferrell,

• Öberg, Carl Mikael, Lunds Universitet, Lund, Sweden

Carl Mikael Öberg,

• Buchsbaum, Steven F., Lawrence Livermore National Laboratory, Livermore, California, United States

Steven F. Buchsbaum,

• Jue, Melinda L., Lawrence Livermore National Laboratory, Livermore, California, United States

Melinda L. Jue,

• Wang, Dan, The Ohio State University, Columbus, Ohio, United States

Dan Wang,

• Roy, Shuvo, University of California San Francisco, San Francisco, California, United States

Shuvo Roy,

• Fornasiero, Francesco, Lawrence Livermore National Laboratory, Livermore, California, United States

Francesco Fornasiero,

• Fissell, William Henry, Vanderbilt University Medical Center, Nashville, Tennessee, United States

William Henry Fissell,

Background

Size selective molecular separation offer transformative advances in hemodialysis. The classic trade-off between selectivity and permeability necessitates larger membrane areas (larger kits) and high pressures in conventional dialysis membranes, which limits progress towards implantable/wearable alternatives. Here, vertically aligned nanoscale capillaries embedded in a polymer matrix present new possibilities.

Methods

Vertically aligned carbon nanotubes (CNTs) forests were synthesized via chemical vapor deposition with precise diameter control via catalyst engineering and the space between was filled with paralyene. A microporous silicon support was used as a backing plate and the membranes mounted into a custom-built filtration cell. Hydraulic permeability was assessed via gravimetric flow rates at different transmembrane pressures. The transport of fluorescently labeled polydisperse Ficoll, either in phosphate-buffered saline (PBS) or bovine blood plasma was used to evaluate the size-selectivity. Ficoll concentrations were analyzed using size-exclusion chromatography.

Results

The synthesized CNT membranes membrane exhibited a cut-off ~6nm for Ficoll in PBS as well as bovine blood plasma. We measured a hydraulic permeability ~102.3 ml h^-1 m^-2 mm Hg^-1 in comparison to ~30 ml h^-1 m^-2 mm Hg^-1 reported in the literature for conventional high flux dialyzers. The CNT membranes allow for near complete passage of ~2 nm Ficoll molecules (Figure), which is similar to the approximate size of hemodialysis relevant small/middle molecules, e.g. b₂ microglobulin, while maintain clinically acceptable levels of Albumin loss.

Conclusion

The synthesized CNT membranes showed enhanced middle molecule clearance as well as higher hydraulic permeability compared to conventional hemodialysis membranes.

Funding

• Other U.S. Government Support