New DNA computer can assess water quality

Synthetic biologists at Northwestern University have developed a low-cost, easy-to-use handheld device that lets users know in just a few minutes whether their water is safe to drink

The new device works by harnessing a powerful network of programmable genes that mimic electronic circuits that perform a range of logical functions

In DNA-based circuits, for example, the researchers engineered cell-free molecules into analog-to-digital converters (ADCs), a type of circuit ubiquitous in nearly all electronic devices

The research will be published Feb.

The device consists of 8 small test tubes that glow green when contaminants are detected

"We set a different contamination threshold for each pipe," said Julius B.

Lukes is a professor of chemical and biological engineering in Northwestern's McCormick School of Engineering and a member of the Center for Synthetic Biology

The new system builds on work by Lacks and his team published in the journal Nature Biotechnology in July 2020

To develop ROSALIND, Lacks and his team employed cell-free synthetic biology

"We discovered how bacteria naturally taste things in their water," he said

Now, in a new version called ROSALIND 2.

"The original platform was a biosensor that acted like a taste bud," Lacks said

The researchers freeze-dried the reprogrammed "molecular brains" to make them shelf-stable, then put them in test tubes

To test the new system, Lacks and his team demonstrated that it could successfully detect the concentration levels of zinc, an antibiotic and an industrial metabolite
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Giving pollution levels -- not simply positive or negative outcomes -- is important to inform strategies to reduce emissions, Lucks said
.

"After we launched ROSALIND, people said they wanted a platform that could show concentrations," he said
.
"Different levels of contaminants require different strategies
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For example, if your water is low in lead, then you can live with it by flushing your water pipes before use
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But if your water is high, then you need to immediately Stop drinking water and change water pipes
.
"

Ultimately, Lacks and his team hope to enable people to regularly test their water
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With an inexpensive handheld device like Rosalind, that could soon become a reality
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"It's clear that we need to empower people to use information to make important and sometimes life-saving decisions," Lacks said
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"We're seeing this with home testing for COVID-19
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People need to be tested at home because they need quick and regular information
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It's similar to water
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In many cases, water quality needs to be measured routinely
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It's not a one-off things, because pollution levels can change over time
.
"

article title

Programming cell-free biosensors with DNA strand displacement circuits