Single-molecule PFAS Analysis with Nanopores (SPAN)

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are emerging environmental contaminants, commonly found in fire suppressants, landfill leachates, and wastewater treatment plant effluent and solids. Their persistence is of concern due to links with hepatotoxicity, nephrotoxicity, thyroid damage, developmental toxicity, and endocrine disruption. As we learn more about the extent of PFAS contamination and its toxicity, the need for rapid detection becomes critical. Current methods like LC-MS/MS, GC-MS, and ion mobility offer sensitive detection but face limitations such as low throughput, high detection limits, high costs, and operational complexity. Emerging techniques have shown promise but cannot yet detect PFAS at extremely low concentrations with reliability. Our goal is to develop a faster, more cost-effective, yet robust solution for PFAS detection.This project will pioneer an advanced solid-state nanopore chip designed to address these urgent needs.A solid-state nanopore is a nanoscale hole, typically with a diameter ranging from a few nanometers to hundreds of nanometers, drilled into an inorganic material such as silicon nitride (SiNx). The basic nanopore setup involves an electrolytic solution separated by the nanopore. When a voltage is applied, charged molecules are driven through the pore, and the resulting electric current (typically 0.1-1 nA) is measured. Changes in the current, caused by a single particle passing through the pore, reveal information about the particle's properties, such as size, shape, charge, and mass, as well as its interactions with the pore.Our nanopore technology, which has demonstrated single-molecule precision in detecting DNA, RNA, proteins, and small pharmaceuticals, is being adapted for PFAS detection. It includes a low-noise SiNx nanopore chip, a portable nanopore reader, and a barcoding kit. The barcoding kit contains a unique aptamer probe designed to specifically bind to target PFAS molecules. Due to their small size relative to the pore diameter, PFAS molecules alone produce negligible and undetectable current signals. However, when PFAS molecules bind to the aptamer, forming PFAS-aptamer complexes, the resulting signal exhibits deeper current blockages and longer translocation times compared to aptamer-only or PFAS-only cases. These pronounced and distinct signals enable reliable detection through nanopore measurements.Through innovative nanofabrication, high-throughput data collection, and advanced analysis, we will enhance improved detection capabilities of PFASs. Tailored chips with optimized nanopore characteristics (diameter, thickness, materials, coating, etc.) will be fabricated, tested, and evaluated for storage, stability, and reusability. We envision this technology as a key tool for environmental protection, providing a first line of defense against PFAS contamination for individuals and public or private organizations, with the potential for broader applications in contaminant detection.