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Wei Group Develops Portable Tech for Detecting Cyanotoxins in Water

This article is a modified version of an article written by Matt Shipman, Research Lead in University Communications.

Professor Qingshan Wei and his colleagues have developed the first portable system – based on smartphone technology – that can test for cyanotoxins in water.

Cyanotoxins are toxic substances produced by cyanobacteria (a.k.a. “blue-green algae”). At high enough levels, cyanotoxins can cause health effects ranging from headache and vomiting to respiratory paralysis and in rare circumstances, death. Cyanotoxins are especially toxic to canines.

The new technology is capable of detecting four common types of cyanotoxins: anatoxin-a, cylindrospermopsin, nodularin and microcystin-LR. One reason the portable technology may be particularly useful is that EPA finalized water quality criteria in June 2019, for both 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,” says Professor Wei, the 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.”

The technology and the portable system will be useful in many settings. For instance, an article in the journal toxins describes water samples taken from Jordan Lake between 2014 and 2016 by the North Carolina Department of Environmental Quality that contain anatoxin-a, microcystin and cylindrospermopsin in small concentrations. Jordan Lake supplies drinking water for Morrisville, Cary, and Apex.

Cyanotoxin DetectorTo test for cyanotoxins, users place a drop of water on a customized 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 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,” says 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 says. “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 the journal Analytical Chemistry. The paper was co-authored by Shengwei Zhang, a Ph.D. student in Prof. Wei’s research group; Tao Yu, a postdoctoral researcher in the Wei group; Zhiming Dai, a B.S. in Computer Science graduate; and Professor Wei.

This work was supported by the Chancellor’s Faculty Excellence Program.