Protein pores found in cell membranes were incorporated at high density into polymer sheets that were stacked to create highly efficient filtration membranes. Image: Cockrell School of Engineering, The University of Texas at Austin.A multidisciplinary team of researchers has developed a new class of protein-based filtration membranes that are faster to produce and higher performing than current technology. These membranes could reduce energy consumption, operational costs and production time in industrial separations, making them useful for a variety of applications, from water purification to small-molecule separations to contaminant-removal processes.
Led by Manish Kumar, associate professor in the Cockrell School of Engineering at The University of Texas at Austin (UT Austin), the research team reports the new high-performance membranes in a paper in Nature Materials.
These filtration membranes possess a higher density of pores than found in commercial membranes and can be produced much faster – in two hours, versus the several-day process currently required. Until now, integrating protein-based membranes into the technology used for industrial separations has been challenging because of the amount of time needed to create these membranes and the low density of protein pores in them.
This study brought together engineers, physicists, biologists and chemists from UT Austin, Penn State, the University of Kentucky, the University of Notre Dame and the company Applied Biomimetic. It presents the first end-to-end synthesis of a true protein-based separation membrane with pores between 0.5nm and 1.5nm in size.
The membranes created by the researchers are biomimetic, meaning they mimic systems or elements of nature, specifically those that naturally occur in cell membranes for transporting water and nutrients. The high-density packing of protein channels into polymer sheets forms protein pores within the membrane, similar to those seen in human eye lenses, but within a nonbiological polymer environment.
The researchers fabricated three different biomimetic membranes, demonstrating a sharp, unique and tunable selectivity with three different pore sizes formed by the protein channels. The methods described can be adapted by inserting protein channels of different pore sizes or chemistries into polymer matrices to conduct specifically designed separations.
"In the past, attempts to make biomimetic membranes fell far short of the promise of these materials, demonstrating only two to three times improvement in productivity," said Yu-Ming Tu, a UT Austin chemical engineering doctoral student and lead on the study. "Our work shows a surprising 20 to 1000 times improvement in productivity over the commercial membranes. At the same time, we can achieve similar or better separation of small molecules, like sugars and amino acids, from larger molecules, like antibiotics, proteins and viruses."
This high productivity was made possible by the very high density of pore proteins in the membrane. Approximately 45 trillion proteins can fit onto a membrane the size of a US quarter, although the membranes created were actually 10–20 times larger in area. This makes the pore density 10 to 100 times higher than in conventional filtration membranes with similar nano-sized pores. Additionally, all the pores in these membranes are exactly the same size and shape, allowing them to better retain molecules of desired sizes.
"This is the first time that the promise of biomimetic membranes involving membrane proteins has been translated from the molecular scale to high performance at the membrane scale," Kumar said. "For so long, engineers and scientists have been trying to find solutions to problems only to find out nature has already done it and done it better. The next steps are to see if we can fabricate even larger membranes and to test whether they can be packaged into flat sheet and spiral-wound-type modules like the ones common in industry."
This story is adapted from material from The University of Texas at Austin, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.