Per- and polyfluoroalkyl substances (PFAS) are a group of man-made "forever chemicals." They're often used in nonstick cookware, stain- and water-resistant fabrics, and firefighting foams. When they contaminate the environment (such as groundwater), they can lead to serious human health risks. Existing methods to measure PFAS are expensive and technically complex. In this work, researchers studied atomically precise nanoclusters as a sensor for PFAS.
The team discovered that interactions with PFAS molecules modify the cluster's light emission. In turn, the cluster lights up. This optical detection is fast and reliable. It has a detection limit of 0.4 parts per billion, which is better than similar current techniques. It is also easy to deploy, as users can mix the nanoclusters into water. Lastly, it avoids unintended reactions with other molecules typically found in environmental samples. These favorable properties make this method suitable for use in several real-world applications, such as water treatment facilities.
The Impact
This new method enables rapid and inexpensive detection of PFAS. It could lead to users being able to evaluate exposure to PFAS more efficiently and map PFAS-contaminated areas faster. It also holds promise as a screening tool in the field to assess the efficiency of PFAS remediation. These results lay the foundation for scientists to create even more advanced molecular designs of fluorescent clusters for sensing applications.
Summary
This study reports on a new class of nano-clusters, showing that they can be used as sensors for PFAS detection. The cluster cores are atomically precise arrangements of Cerium with glycine molecules. The optical properties of these materials were measured at the Center for Functional Nanomaterials, a Department of Energy Office of Science User Facility at Brookhaven National Laboratory. These clusters exhibit fluorescent light emission in the ultraviolet wavelength (353 nm), which can be used for PFAS detection.
In particular, the fluorescence is sensitive to long chain PFAS molecules, such as perfluorooctanoic, perfluorononanoic, and perfluorodecanoic acids. The unique reactivity between the clusters and PFAS leads to a change in the emission spectra in a manner that changes with concentration. The reaction-and thus detection-is robust against interference from other molecules that often co-occur with PFAS. These molecules include sulfonated PFAS, octanoic and dodecanoic acids, humic acid, and inorganic ions. At optimal concentrations, the method demonstrated detection limits of 0.2–0.4 part per billion. This straightforward procedure can be seamlessly integrated with conventional spectrofluorometric equipment. These findings highlight the potential of fluorescence-based detection strategies utilizing nanoscale probes for simple PFAS detection.
Funding
This work was supported by the National Science Foundation and the New York State Center of Excellence. This research used resources at the Center for Functional Nanomaterials, which is a U.S. Department of Energy Office of Science User Facility.