Assessing albumin-PFAS interaction by ion-transfer electrochemistry at a liquid-liquid micro-interface array

• Transfer voltammetry of ionised PFAS at liquid-liquid interface is achieved • But the transfer current is diminished in the presence of bovine serum albumin • PFAS-BSA binding occurs and may be quantified • Binding constants for PFAS-BSA complexes were determined Per- and polyfluoroalkyl substances (PFAS) are persistent, ubiquitous anthropogenic chemicals that have potential health impacts for humans. Here, we investigate ion-transfer voltammetry of a range of ionised PFAS in the presence of bovine serum albumin (BSA) using an array of micro-interfaces between two immiscible electrolyte solutions (µITIES) in order to determine their binding interactions. The experimental results reveal that the electrochemical signals, interfacial ion-transfer currents, of the aqueous phase ionised PFAS are decreased in the presence of BSA in the same phase, which is attributed to complexation of PFAS by BSA. Titration curves are established for each PFAS-BSA combination by measuring the ion-transfer current of free PFAS anions at different concentrations of BSA. Fitting of the obtained data to a binding isotherm enables determination of the binding or association constants of the PFAS-BSA complexes. The measured binding constants of the studied ionised PFAS (perfluorooctanoate, perfluorooctanesulfonate, perfluoroheptanoate and perfluorobutanesulfonate) with BSA were in the range of 10 4 – 10 6 M −1 . The µITIES array electrochemical method provides a simple way to generate information on binding interactions of PFAS with protein that may be useful in assessing toxicity and bioaccumulation of PFAS.