New Water Treatment Potential from Mimicking Kidney

Researchers at the University of Illinois (Urbana-Champaign campus) have taken the first step toward creating a membrane for moving water, and nothing but water, by mimicking the action found in kidneys. If they are successful in scaling up the size, their method promises to be at least 10-times more effective at desalinization and water purification than current methods, a critical technology for areas with poor water supplies, or in semiarid coastal regions.

Researchers in the lab of Mark Clark, professor of civil and environmental engineering and in Basil, Switzerland took a close look at how kidneys so effectively transported water via their membranes, and created a biomimetic membrane based on the Aquaporin Z protein extracted from E. coli bacteria. A biomimetic compound is one that mimics the behavior of a biological system.

“We took a close look at how kidneys so efficiently transport water through a membrane with aquaporins, and then we found a way to duplicate that in a synthetic system,” said Manish Kumar, a graduate research assistant at the U. of I., and the paper’s lead author in a press release from Illinois.

The researchers created the biomimetic membrane by using a polymer permeable to water, and before they could close into a vesicle, inserting and encapsulating the Aquaporin Z.

Another potential use for the new polymer is for drug transport, since it only selectively permits compounds to pass through. “By varying the amount of Aquaporin Z, we can vary the membrane’s permeability,” Kumar said, “which could be very useful for drug-delivery applications.”

One of the advantages that the biomimetic polymer has over biological membranes is strength and durability. Both features are critical for the potential use in water purification and desalinization, in which significant pressures are applied to current reverse-osmosis filters in order to purify water at a usable rate.

Currently the membranes only exist as microscopic vesicles, and additional work lies ahead to create larger-scale membranes for practical applications. Additional testing and tweaking to the structure of the membrane should also lead to greater control of permeability according to Kumar.

The paper has been accepted for publication in the Proceedings of the National Acadamies of Science, and is scheduled to appear in the Early Online Edition November 30. Co-authors also include research professor Julie Zilles at the U. of I., and chemistry professor Wolfgang Meier and doctoral student Mariusz Grzelakowski, both at the University of Basel in Switzerland.