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A Vanderbilt-led research team has made a significant breakthrough in developing advanced dialysis membranes using atomically thin materials like graphene. These innovative membranes, called nanoporous atomically thin membranes (NATMs), leverage a protein-enabled sealing mechanism to address a key challenge in dialysis technology, which is maintaining high efficiency in filtering small molecules while minimizing protein loss.

The work is in the journal Nano Letters.

Dialysis membranes must balance two critical functions: allowing small molecules to pass through for removal while preventing the leakage of vital proteins. The team's approach uses the unique properties of graphene—its extreme thinness and customizable nanopores—to enable precise and rapid filtration. However, even a single large pore can cause excessive leakage, compromising the membrane's performance.

To tackle this, the researchers developed a novel method that transforms protein leakage into an advantage. When proteins escape through larger pores, they react with molecules on the other side of the graphene membrane. This reaction triggers a sealing process, selectively closing larger pores while preserving smaller ones.

This self-sealing capability ensures precise size-selective filtration and improves the membrane's overall effectiveness.

"The ability to seal inconsistent pore sizes and selectively filter molecules based on size represents a new paradigm for dialysis membranes," said Peifu Cheng, research assistant professor of chemical and biomolecular engineering and first author of the study.

"Proteins and biomolecules have a natural flexibility that allows them to deform slightly when passing through nanopores," Cheng explained. "Our approach builds on this property, significantly advancing beyond current dialysis technologies and commercially available membranes."

Assistant Professor of Chemical and Biomolecular Engineering Piran Kidambi, who led the project, emphasized the groundbreaking nature of the work. "Our study introduces proteins as nanoscale tools to engineer pore sizes in atomically thin membranes, overcoming critical challenges in current dialysis systems.

"To the best of our knowledge, this is the first demonstration of such a method, and it opens the door to utilizing a wide range of biomolecules—including DNA and RNA—for precise membrane fabrication."

The team demonstrated this protein-enabled size-selective defect sealing (PDS) method on centimeter-scale graphene membranes. These defect-sealed NATMs remained stable for up to 35 days and consistently outperformed state-of-the-art commercial dialysis membranes.