Vanderbilt team reimagines kidney dialysis by creating new paradigm for dialysis membranes

A collaborative team led by Piran Kidambi, assistant professor of chemical and biomolecular engineering, William Fissell, associate professor of nephrology and hypertension at Vanderbilt University Medical Center, Shuvo Roy, professor of bioengineering at University of California, San Francisco, and Francesco Fornasiero, biosciences and biotechnology staff scientist at Lawrence Livermore National Lab, has developed a new type of filter for kidney dialysis machines that can clean the blood more efficiently and improve patient care.

Chronic kidney disease, a condition where kidney damage results in poor blood filtration, affects approximately 697.5 million people—or 9 percent of the global population. Treatment includes hemofiltration, hemodialysis or kidney transplantation. Hemofiltration and hemodialysis support the kidneys by filtering toxins and waste products from blood.

The new filter uses carbon nanotubes—tiny tubes formed by a sheet of carbon atoms bonded in a hexagonal honeycomb mesh structure—that have very small, smooth channels. These channels make it easier to remove toxins and waste from the blood without letting important proteins escape, which can be a problem with traditional filters.

In the article “High-Performance Hemofiltration via Molecular Sieving and Ultra-Low Friction in Carbon Nanotube Capillary Membranes,” published in the journal Advanced Functional Materials on Aug. 27, Kidambi and his co-authors demonstrate that their dialysis membranes made up of carbon nanotubes and polymers create a new paradigm for dialysis.

portrait in lab
Piran Kidambi (Vanderbilt University)

“Our membranes outperform state-of-the-art dialysis membranes by more than an order of magnitude while simultaneously allowing for enhanced removal of middle molecules that could cause toxicity and other health complications,” Kidambi said. “We showed that precise control of carbon nanotube diameters not only allowed for enhanced and effective removal of middle molecules, but the straight channel geometry as well as slippery walls of the nanotubes allowed for significantly enhanced flow.”

The work also yielded fundamental insights on how biomolecules transport in nanoscale constrictions. Like an octopus that can contort itself to fit in the smallest spaces and then expand, Kidami and his co-authors discovered that biomolecules squeeze into the entrance of the nanotube in the membrane, travel through it and expand again on the other side. This knowledge can help researchers and engineers design membranes for biological separations beyond dialysis.