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New biosensor aims to help fight permanent chemical bond

Per- and polyfluoralkyl substances (PFAS) are a family of synthetic compounds used globally to make products that resist heat, oil, stains, grease and water. The compounds break down very slowly over time and are recognized as an “emerging contaminant” with widespread concerns about their characteristics of persistence, bioaccumulation, toxicity, mobility and impacts on human health.

 

One company focused on addressing these “forever chemicals” is Allonnia. Describing themselves as a “bio-ingenuity company”, they recently announced that they have discovered a protein that can be used as a PFAS biosensor. The patent pending protein can detect the presence of PFAS down to parts per trillion, levels as low as a single drop in an Olympic-sized swimming pool.

 

To learn more about the biosensor and its potential in real-world applications, we spoke to Dayal Saran, vice president and head of research, Allonnia and Kent Sorenson, chief technical officer, Allonnia.

 

Ash Board (AB): Can you outline what PFAS are and why they are recognized as an “emerging contaminant”?

Kent Soreson (KS): PFAS are man-made, bioaccumulative toxic compounds used in various consumer and industrial products. These compounds comprise thousands of chemicals characterized by their carbon-fluorine bonds, the strongest chemical bond in nature. This bond strength makes PFAS very difficult to degrade and persistent in the environment; therefore, these compounds are also known as “forever chemicals”. Some are complex molecules like those used to make Teflon, non-stick pans, firefighting foam or stain-resistant fabric. PFAS contaminants are considered “emerging” because they’re being detected, often at high levels, in more and more sources of water globally and pose a threat to human health and the environment. Recently published data have shown that PFAS are present in the blood of humans and animal populations even in the most remote locations on Earth.

 

AB: Allonnia has announced that it has discovered a protein that can be used as a PFAS biosensor. Can you explain more about the protein and how it detects PFAS?

Dayal Saran (DS): At Allonnia, we have selected and identified proteins from a library of around 1012 (one trillion) unique proteins that have high affinity and selectivity for specific PFAS compounds (perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)). Currently, we are in the process of immobilizing these proteins on an electroactive surface that generates an electrochemical signal when these proteins recognize PFAS compounds.

 

When a sample of PFAS-contaminated water or wastewater interacts with the protein, the PFAS detection is captured through an electro-chemical signal that is converted to a digital signal for measurement. The sensor is currently being designed to detect PFOA, one of the most common PFAS, in real-time at concentrations as low as a few parts per trillion in water. The Allonnia team is working to validate the biosensor’s capability to detect other PFAS molecules.

 

AB: What are the benefits of using a biosensor over traditional sensors to detect PFAS contaminants? How does the sensitivity and specificity of the biosensor compare to other sensors currently on the market?

 

DS: There is currently no PFAS sensor on the market that can detect PFAS contaminants at these low levels in real-time. Most customers send samples to off-site labs to detect the PFAS contamination. Analytical methods mostly employ lab-based liquid chromatography-mass spectrometry (LC-MS) which has the advantage of high sensitivity and low detection limits but suffers from being expensive, time-intensive (usually three to four weeks turnaround time) and requires specialized personnel for operation.

The benefits of a biosensor include the ability to detect contaminants with high sensitivity, ease of operation in a portable detection tool with high selectivity and specificity to PFAS, and more efficiency as they provide immediate, on-site detection with zero or minimal pretreatment and no associated shipment costs.

 

AB: Allonnia is working to bring the patent-pending Gen 1 protein to the field. What further developments are required for the protein to be commercialized?

 

DS: Allonnia is working with a hardware partner to bring a prototype test-kit solution into the field. Our technical team also continues work to increase the sensitivity of the protein and its specificity to PFAS in real-world groundwater.

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