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Two surprising discoveries, one abundant resource

The next revolution in medicine and sustainability is in the water

Just down the hall from each other, two Northwestern University nanotechnology scientists accidentally stumbled on separate revolutionary discoveries. Between them, they may diminish the need for multiple surgeries in patients and transform water filtration — all by harnessing previously unknown powers of the world’s most abundant resource: water.

John Rogers, Director of the Center for Bio-Integrated Electronics, is developing devices that will have major implications in medicine. William Dichtel, Robert L. Letsinger Professor of Chemistry, is working on organic and polymer chemistry and nano fabrication — essentially, how to build devices with individual molecules. The research of Rogers and Dichtel show new ways that water can improve patient outcomes and promote sustainability.


Healing the body: silicon's surprising properties

John Rogers and his team of researchers recently made a significant discovery: silicon — long thought to be a permanent material, like rock or brick — actually dissolves in water when sliced into incredibly thin sheets.

John Rogers
John Rogers, PhD, Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery

The discovery was mostly serendipitous. “We weren’t testing silicon for its ability to dissolve, we were interested because of its ability to bend by virtue of its tiny thickness,” Rogers says. “We had developed a way to take silicon wafers and shave them down to sheets with a thickness of maybe a tenth of a micron. In creating and manipulating that silicon, we stumbled across the fact that it dissolves, although very slowly, in water and biofluid, and that the end products are biologically benign, naturally occurring in the body.”

This discovery in “bio-resorbability” — the capacity to be absorbed naturally into the human body — has remarkable medical applications. For example, an electronic device could be constructed from silicon and inserted into the body to accomplish a specific task. Then, once its purpose has been served, it dissolves (see animation below). Take severe brain injuries: currently, a neurosurgeon has to insert a monitoring device into the skull to ensure the brain’s temperature and pressure stay within a safe zone. A second surgical procedure is then required to remove the device after this critical monitoring period ends.

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With a bio-resorbable material, “you can eliminate the dangers and complications associated with a secondary surgery for extraction, while still providing that critical monitoring function for the risk period associated with a recovery and healing process,” Rogers says. “We’ve demonstrated this in animal models — fully bio-resorbable pressure and temperature sensors that make measurements with clinical-grade quality in the intracranial space, but eventually dissolve.”

With human trials up next, Rogers and his research team believe their discovery can advance medical treatments and fundamentally improve patient care.


Helping the planet: a new way to clean water

Down the hall from Rogers is the lab of William Dichtel, who is working with water outside the human body. Dichtel’s team’s research into organic and polymer chemistry and nanofabrication — how to assemble molecules into electronic or energy-storing devices — led to the discovery of a new material that can more efficiently purify water.

William Dichtel
William Dichtel, PhD, MacArthur fellow and Robert L. Letsinger Professor of Chemistry

About two years ago, Dichtel’s group joined the Center for Sustainable Polymers (CSP) at the University of Minnesota, where researchers develop plastics and organic materials from non-petroleum-based resources. A post-doctoral student on Dichtel’s team, Alaaeddin Alsbaiee, suggested applying their nanostructured polymers — material made from joining smaller molecules with pores at the nanometer scale – to water. They did just that, and the result was incredible. “I just about fell out of my chair,” says Dichtel.

Dichtel and Alsbaiee worked with environmental engineers to perform more rigorous tests, and were thrilled when the results held. Their new material “just pulled pollutants out of water instantaneously,” Dichtel explains. “Like a sponge, it has a high-surface area with small voids such that water and pollutants can flow through it. Like a magnet, it attracts the pollutants and then binds them to the surface.”

This nano-material is already poised for widespread commercial and industrial uses in respirators, sensing devices, and even household water filters. But Dichtel and his team hope their material can ultimately facilitate large-scale water purification efforts in the developing world, in addition to addressing environmental issues like restoring decimated fish populations.


Harnessing intuition

Both Rogers’ and Dichtel’s work is rooted in the same core concepts: improving mankind through technology and medicine, and transforming the future for worldwide populations. Their efforts begin by “following the science,” as Rogers says — simply staying receptive to unforeseen possibilities and unexpected applications. That intellectual openness and practiced intuition fuels their passion to harness the properties of known materials like water, and to generate significant transformations.

“Northwestern really prides itself on research and discoveries with downstream applications,” Dichtel says. “Having an impact always is the dream, especially if it can make someone else’s life better.”

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