Beyond persistence: SERS-driven strategies for PFAS detection and monitoring

This review explores surface-enhanced Raman spectroscopy (SERS)-driven strategies for the detection and monitoring of per- and polyfluoroalkyl substances (PFAS), a class of nearly 15,000 synthetic compounds known for their exceptional chemical stability and environmental persistence. Due to the high bond dissociation energy of carbon-fluorine bonds, PFAS accumulate globally in water and soil, posing severe risks to human health, including cancer, liver toxicity, and immune suppression. As regulatory bodies like the U.S. EPA establish stringent maximum contaminant levels as low as 4 ng/L (ppt level), there is an urgent demand for rapid, cost-effective, and portable sensing platforms to complement traditional, high-cost analytical techniques like LC-MS/MS. SERS is highlighted as a powerful analytical tool capable of providing ultra-sensitive "molecular fingerprinting" by amplifying Raman signals through localized surface plasmon resonance (LSPR) on metallic nanostructures. This paper categorizes the fundamental mechanisms of SERS-based PFAS detection into three primary interaction strategies: (1) host-guest inclusion using molecular cavities like β-cyclodextrin or MOFs, (2) covalent bonding between PFAS functional groups and substrate surfaces, and (3) physical adsorption driven by hydrophobic and electrostatic forces. Despite its potential, practical SERS deployment faces challenges such as weak PFAS-surface affinity and spectral interference from complex environmental matrices. To address these, the review discusses emerging advancements, including fluorophilic surface functionalization, deep learning-based spectral deconvolution, and the integration of microfluidic platforms for real-time monitoring. Ultimately, these SERS-driven innovations provide a critical pathway toward achieving on-site, high-throughput quantification of trace PFAS in diverse water resources.