Portable device detects potentially fatal cyanotoxins

A low-cost, portable technology has been developed that can be used to detect cyanotoxins, which are waterborne substances that can be fatal in high concentrations.

Screenshots of the smartphone app of the cyanotoxin sensor. Left: Welcome page. Right: Data analysis page

Developed at North Carolina State University (NC State), the device – claimed to be the first of its kind – can be used to detect four common types of cyanotoxins, including two for which the U.S. Environmental Protection Agency (EPA) recently finalised recreational water quality criteria.

Cyanotoxins are produced by cyanobacteria and at high enough levels can cause adverse health effects ranging from headache and vomiting to respiratory paralysis and death.

According to NC State, the new technology can detect anatoxin-a, cylindrospermopsin, nodularin and microcystin-LR. One reason the portable technology may be particularly useful is that EPA finalised water quality criteria in June, 2019 for microcystin-LR and cylindrospermopsin in recreational waters.

“Our technology is capable of detecting these toxins at the levels EPA laid out in its water quality criteria,” said Qingshan Wei, an assistant professor of chemical and biomolecular engineering at NC State and corresponding author of a paper on the work.

“However, it’s important to note that our technology is not yet capable of detecting these cyanotoxins at levels as low as the World Health Organization’s drinking water limit. So, while this is a useful environmental monitoring tool, and can be used to assess recreational water quality, it is not yet viable for assessing drinking water safety.”

To test for cyanotoxins, users place a drop of water on a customised chip developed in Wei’s lab, then insert it into a reader device, also developed in Wei’s lab, which connects to a smartphone. The technology is reportedly capable of detecting and measuring organic molecules associated with the four cyanotoxins, ultimately providing the user’s smartphone with the cyanotoxin levels found in the relevant water sample. The entire process takes five minutes.

“The reader cost us less than $70 to make, each chip cost less than a dollar, and we could make both even less expensive if we scaled up production,” said Zheng Li, a postdoctoral researcher at NC State and first author of the paper.

“Our current focus with this technology is to make it more sensitive, so that it can be used to monitor drinking water safety,” Wei said in a statement. “More broadly, we believe the technology could be modified to look for molecular markers associated with other contaminants.”

The paper, “Aptamer-Based Fluorescent Sensor Array for Multiplexed Detection of Cyanotoxins on a Smartphone,” is published in Analytical Chemistry.