February 24, 2022 | Northwestern Engineering synthetic biologists have developed a hand-held device that can let users know – within minutes – if their water is safe to drink.
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The device works by using powerful and programmable genetic networks, which mimic electronic circuits, to perform a range of logic functions.
Among the DNA-based circuits, for example, the researchers engineered cell-free molecules into an analog-to-digital converter (ADC), a ubiquitous circuit type found in nearly all electronic devices. In the water-quality device, the ADC circuit processes an analog input (contaminants) and generates a digital output (a visual signal to inform the user).
The research was published on February 17, 2022 in the journal Nature Chemical Biology.
How it works
Equipped with a series of eight small test tubes, the device glows green when it detects a contaminant. The number of tubes that glow depend upon how much contamination is present. If only one tube glows, then the water sample has a trace level of contamination. But if all eight tubes glow, then the water is severely contaminated. In other words, the higher concentration of contamination leads to a higher signal.
“We programmed each tube to have a different threshold for contaminations,” said the McCormick School of Engineering’s Julius B. Lucks, who led the research. “The tube with the lowest threshold will light up all the time. If all the tubes light up, then there is a big problem. Building circuits and programmable DNA computing opens up many possibilities for other types of smart diagnostics.”
Lucks is a professor of chemical and biological engineering at Nothwestern Engineering and a member of the Center for Synthetic Biology. The paper’s co-authors include Jaeyoung Jung, Chloé Archuleta, and Khalid Alam – all from Northwestern.
Improvement of a previous developed system
The new system builds off work that Lucks and his team published in Nature Biotechnology in July 2020. In that work, the team introduced ROSALIND (named after famed chemist Rosalind Franklin and short for “RNA output sensors activated by ligand induction”), which could sense 17 different contaminants in a single drop of water. When the test detected a contaminant exceeding the US Environmental Protection Agency’s standards, it either glowed green or not to give a simple, easy-to-read positive or negative result.
Now, in the new version – dubbed ROSALIND 2.0 – Lucks and his team have added a “molecular brain.”
“The initial platform was a bio-sensor, which acted like a taste bud,” Lucks said. “Now we have added a genetic network that works like a brain. The bio-sensor detects contamination, but then the output of the bio-sensor feeds into the genetic network, or circuit, which works like a brain to perform logic.”
At-home tests allow regular measurement
Ultimately, Lucks and his team hope to empower individuals to test their own water on a regular basis. With inexpensive, hand-held devices like ROSALIND, that may soon become a reality.
“It’s clear that we need to enable people with information to make important, sometimes lifesaving decisions,” Lucks said. “We’re seeing that with at-home tests for COVID-19. People need at-home tests because they need that information quickly and regularly. It’s similar with water. There are many cases where water quality needs to be measured routinely. It’s not a one-time thing because contamination levels can change over time.”
Source: Northwestern University