Stanford scientists create contaminant-cleaning ‘nanoscavengers’

May 30, 2013, 11:51 p.m.

Communities with limited access to clean water look set to benefit from the recent fabrication of “synthetic nanoscavengers,” which can clear out harmful contaminants from water, by an interdisciplinary team of Stanford scientists.

“The filtering entity is static; the water molecules are moving,” explained Shan Wang, professor of materials science and engineering and senior author of the study. “In this technology, the nanoparticles are moving in water, and the bacteria are moving in water… so the killing action can be much faster.”

The nanoscavengers, which are coated with a layer of silver or titanium dioxide, randomly collide with and kill bacteria while floating around in contaminated water. Since they have a large magnetic moment, the particles can also be easily retrieved.

“It’s a very simple idea, but it works beautifully,” Wang said.

The team’s next step is to extend this technique to target other inorganic and organic contaminants, such as heavy metals.

“If our nanoparticle is coated with different materials, then we can tackle all of those problems in one,” said Mingliang Zhang M.S. ’12 Ph.D. ’13, a doctoral candidate in materials science and engineering and co-first author of the study.

At this stage, however, the team is limited in output by their production technique.

“We are still improving the technique; we are looking for different strategies to make this type of particle,” Zhang said.

Nanoprinting could offer one futuristic opportunity for producing particles in a cost-efficient way.

“Eventually the material cost will be the main cost– the silver itself– but you can recycle it 10,000 times,” said Xing Xie M.S. ’12 Ph.D. ’13, a doctoral candidate in civil and environmental engineering and co-first author of the paper.

The team’s research on water purification also has other applications.

“Water treatment is just one use,” Zhang said. “I’m also working on using nanosynthesis to synthesize a device for molecular imaging.”

Shan said it has been particularly exciting to see the research’s potential ability to fix significant real-world problems.

“I feel that being able to innovate and come up with simple but really interesting, out-of-the-box ideas to solve pressing needs in society is really exciting,” Shan said.

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