Toward Comprehensive In Vitro Evaluation of Serum Albumin Binding of Per- and Polyfluoroalkyl Substances.

Per- and polyfluoroalkyl substances (PFAS) constitute a large and chemically diverse class of synthetic compounds characterized by one or more fully fluorinated methyl or methylene groups. Many PFAS are toxic, environmentally persistent, bioaccumulative, and highly mobile, resulting in widespread contamination and biological exposure. Across taxa PFAS exhibit affinity for proteins and preferentially accumulates in protein-rich, highly perfused tissues. Protein binding critically influences PFAS distribution, bioaccumulation, toxicity, and elimination. A variety of different approaches for determining bind affinity have existed for decades; however, depending on experimental conditions, calculated affinities can vary over multiple orders of magnitude which limits comparison of protein-PFAS binding affinities across studies and across PFAS chemical space. Addressing this limitation requires robust and standardized experimental platforms capable of rapidly generating quantitative binding data. Among the most important targets is serum albumin-the principal transport protein in vertebrate blood-which plays a central role in governing PFAS toxicokinetics. This review summarizes current methodologies for measuring protein-PFAS binding affinities, evaluates the strengths and limitations of each approach, synthesizes the existing literature on serum albumin-PFAS interactions, and highlights differential scanning fluorimetry as a rapid, reproducible, and sensitive technique for in vitro assessment of relative protein-PFAS binding.