Three Wyss projects aim to reduce global pollution through better detection, greener alternatives, and creating value from waste
By Lindsay Brownell
In honor of Pollution Prevention Week, we’re highlighting three Wyss projects that are taking on the formidable problems of PFAS and plastic – persistent and toxic pollutants that threaten the health of humans, animals, and ecosystems.
PFASense – Finding PFAS contamination at the source
Per- and polyfluoroalkyl substances (PFAS), or “forever chemicals,” are toxic substances that increase the risk of many health conditions including cancer and birth defects. They don’t break down in the environment, and testing has revealed PFAS contamination in water supplies, consumer products, and even our own bodies. Some municipalities have committed to testing their water for PFAS and installing remediation equipment, but PFAS tests aren’t accessible to everyone.
Currently, the only method available to measure PFAS is an analytical chemistry technique called liquid chromatography–mass spectrometry (LC-MS). LC-MS machines typically cost more than $100,000 and require a skilled technician to operate them. As such, they’re usually located at centralized lab facilities, and testing a single sample for PFAS can cost hundreds of dollars and take weeks to generate results.
Simon d’Oelsnitz wants to break that bottleneck in PFAS testing by developing a point-of-contamination diagnostic using bacteria.
“PFAS molecules are structurally very similar to fatty acids, and bacteria have a preexisting systems for binding to and engulfing fatty acids that they encounter in their environment. We aim to repurpose that system by engineering it to instead recognize and internalize PFAS, then produce a signal that we can detect to confirm the presence of PFAS quickly and inexpensively,” said d’Oelsnitz, who is a postdoc co-advised by Wyss Faculty members Pam Silver and Michael Springer.
As part of a Validation Project called PFASense, d’Oelsnitz is leading a team that is focusing on a type of protein called transcription factors. Some of these proteins are bound to strands of DNA and control their expression levels. When a transcription factor’s target molecule binds to a “pocket” region of the protein’s structure, it detaches from its “home” DNA strand, allowing the DNA to be transcribed into mRNA. The team’s goal is to identify a naturally occurring transcription factor and modify the binding sequence of its “pocket” so that it releases from its DNA strand in response to the presence of PFAS.
d’Oelsnitz and his collaborators have already identified 10 to 12 transcription factors that could be repurposed as PFAS sensors, and is searching for more while screening their first candidates for their abilities to bind to PFAS and related fatty acid compounds. They’re also discussing potential collaborations with researchers in the Collins and Ingber labs to see if their idea can synergize with other technologies such as cell-free molecular diagnostics and electrochemical sensors to produce highly portable, affordable, and sensitive PFAS sensors.
“Part of the problem of PFAS is that we just don’t know the extent of the contamination, because tests for them have only recently been developed. In order to clean up pollution, you have to know where it is, and we hope that giving more people access to reliable PFAS testing will produce more accurate knowledge of the scope of the problem so that solutions can be developed faster,” said d’Oelsnitz.
Nixe – A plant-inspired proxy for PFAS
If PFAS are so toxic and persistent, why are they still in use? They’re highly effective at what they do, from quenching fires almost immediately in firefighting foam to repelling water and oil in performance outerwear. In order to truly eliminate PFAS pollution, we need to not only clean up what exists, but also find viable alternatives to PFAS that are non-toxic and also perform many of the same functions. Caroline Dignes, a Research Fellow at the Wyss Institute, thinks she’s found one, inspired by the bumpy, microscopic surface of lotus leaves.
“Given that California, Colorado, and New York have all banned the sale of PFAS-containing clothing starting in 2025, major brands have already begun to switch to PFAS-free solutions. But many of the current alternatives don’t meet the brands’ needs in terms of durability, breathability, or flexibility. Our technology meets all of those needs while also outperforming other non-PFAS substances in terms of water repellency,” said Dignes.
The coating that Dignes is developing consists of a base layer of particles that are less than a nanometer thick coated in an even thinner layer of a hydrophobic polymer. The rough texture of the material helps trap air between the coating and any water that it encounters, further enhancing its water repellency. In tests conducted on polyester fabric, which makes up over 50% of the fibers used in textiles globally, her coating didn’t impact the breathability or flexibility of the fabric, but did make it dramatically more water-repellent. It also held up in repeated wash tests representing well over a year’s worth of washing at the University of Massachusetts – Lowell’s Fabric Discovery Center.
As part of her Validation Project named Nixe, Dignes is currently working on a paper that will detail her research and results to date, and investigating alternative application processes that will allow her coating to be applied to fabric at a much larger scale for industrial production.
“Having worked in textiles for several theaters and opera houses for years before coming to Harvard, I understand the performance requirements of garments that get heavily worn and washed. Our team is excited about our solution to the PFAS problem because it performs better than commercially available PFAS-free solutions in the lab. We’re looking forward to bringing it to the market to enable a future where all clothing is PFAS-free,” said Dignes.
Using bacteria to solve our pernicious plastic problem
Beyond clothing and textiles, PFAS are also used in many plastic products. And plastic is a big problem in and of itself: more than 350 million metric tons of plastic waste is produced every year – that’s more than 5 million elephants’ worth. Peter Nguyen, a Senior Staff Scientist at the Wyss Institute, points out that this is not the first time the Earth has been beset by a build-up of material that won’t break down. About 350 million years ago, it was trees.
The cell walls of trees are largely composed of a polymer called lignin that supports their growth and helps transport water. But when lignin arrived on the evolutionary scene, there were no organisms on the planet that could break it down, and dead trees simply lay where they fell – much like plastic today. After about 60 million years, an ancestor of a white rot fungus evolved the ability to eat lignin and release its molecules back into the environment. The fact that life found a way to eat a previously inedible substance gives Nguyen hope that it can happen again with plastic, but this time, we don’t have 60 million years to wait.
For his project, Nguyen is focusing on an enzyme that was discovered in a naturally occurring soil microbe a few years ago. This enzyme rapidly degrades PET plastic, one of the most prevalent types that is generally used to make plastic bottles for beverages and oils. Nguyen and his team identified a different microbe that naturally produces PHA, a biodegradable form of polyester that can be used to produce bioplastics, and are working to insert the gene for the PET-degrading enzyme into it. The resulting microbe would thus be able to break down PET into its constituent parts, then use those metabolites to build PHA, which would be harvested and processed into an Earth-friendly alternative to plastic.
“There’s been a lot of excitement about using PHA rather than petroleum as a base material for plastics, but PHA costs 3-10 times more than plastic to manufacture because its feedstocks are things like starches and sugar – materials that are valuable for other uses, and thus higher-cost. Plastic waste currently has no value, which means it can be a virtually free source of PHA feedstock, enabling us to couple the process of breaking down plastic waste with producing something of value, affordably,” said Nguyen.
To further enhance their microbe’s plastic-eating abilities, Nguyen’s team in the Collins lab plans to engineer it to produce multiple different enzymes each specialized to degrade a specific type of plastic. Because the microbe grows easily in room-temperature conditions, they hope to produce a product that can simply be sprayed onto mixed plastics and will degrade all of them within the span of weeks to months, rather than the decades to centuries it takes for most plastics to break down in the environment.
His team’s progress so far is bolstering Nguyen’s confidence that the large-scale change needed to combat plastic pollution is on the horizon. “Every time I look at my recycling bin at home that’s full of plastic, I no longer see it as waste – I see it as food that has the potential to be consumed and used to power useful processes. And microbes are the alchemists that make that possible.”
If you are interested in supporting these projects or learning about other sustainability efforts at the Wyss Institute, please contact Emily Stoler.