By Zichang Liu
Boston University News Service
University of Massachusetts Amherst professors Chang Liu and Xiaojun Wei have discovered a new method to detect per- and polyfluoroalkyl substances – “forever chemicals” found in water, soil, air, food and other consumer products, paving the way for efficient, cost-effective detection devices.
Liu described the finding as “kind of fun by a beautiful accident” with “interesting results by just a wild guess and try,” since this idea emerged while exchanging ideas with colleagues.
PFAS, a toxic contaminant, breaks down slowly and can accumulate in humans, animals and the environment over time. Exposure to PFAS may pose threats to health, including higher risks of various cancers, affect reproductive capabilities, weaken immune system and cause a series of consequential effects to infants and children.
According to a 2019 study conducted using data from the National Health and Nutrition Examination Survey, PFAS chemicals have been detected in the blood of 98% of Americans.
Earlier this year, the Environmental Protection Agency issued the first national enforceable drinking water safety standard to limit toxic PFAS substances, involving nearly 181 water systems in Massachusetts, an estimated 95 of which are required to tackle these contaminants.
In October, EPA later launched new federal regulations requiring all Massachusetts drinking water systems to replace lead pipes within 10 years, supported by a $53.5 million EPA grant to address water contaminants issue.
The EPA’s standard for PFAS in drinking water is set at 4 ppt, which is four parts per trillion molecules in water. This limit is close to the lowest level at which the chemicals can be detected.
However, the current PFAS detection relies on using liquid chromatography combined with mass spectrometry, techniques which requires a million-dollar instrument that is costly and hard to maintain and operate with complicated extraction steps, said Liu, an associate professor at UMass Amherst and the corresponding author of the research published in November.
He added that such instruments are typically found only in universities or well-funded centralized labs.
“The stubborn persistence of PFAS residues can diminish the sensitivity of these instruments over time,” said Wei, the first author of the paper and a research assistant professor at UMass Amherst.
Liu said their instrument would only cost around $10,000 and could be designed as a portable device, working by adding a molecule called cyclodextrin to a nanopore, a small device which is commonly applied to analyze DNA sequences. The “host-guest” interaction between cyclodextrin and PFAS has been well documented, but Liu said that no one had ever combined it with a nanopore for detection.
“The current stage of the technology is proof of concept,” Liu said, explaining that they are still working on making their sensor adaptable to more PFAS molecules among various kinds of families to meet the EPA standard. He also said they are trying to improve their sensor sensitivity to the levels as low as 400 ppt as EPA required. Liu and Wei both foresee the promising potential of its impact.
“Now we’re using one of these molecules called HP-gamma-Cyclodextrin as an adapter in an alpha-Hemolysin nanopore,” he said, effectively creating a PFAS detector. Hemolysins are proteins and lipids that cause red blood cells to break down.
Wei said they are also planning to develop a chemistry-related method to conduct water pre-treatment to ensure the ideal detection performance.
“We’re bringing the cost of the instrument from the scale of a million dollars to a few thousand,” Liu said. “Each test will probably just cost you one dollar or two.”
Liu also stressed the foreseeable improvement of public awareness of PFAS. He said that PFAS regulation had lagged but is now improving, though more effort is needed for remediation.
“Hopefully in the future, the regulation will catch up and then tell us how much PFAS you should expect in your water system without affecting your health,” he said.
Researchers also see a potential application of their method as the first-screening tool to identify the water that poses serious threats to human health.
He said the team is seeking collaboration opportunities with the EPA, National Science Foundation and Massachusetts investors to help advance this technology to the application stage.
