Adsorption of Per- and Polyfluoroalkyl Substances by Edible Nutraceutical-Amended Montmorillonite Clays: In Vitro, In Vivo and In Silico Enterosorption Strategies

Abstract

Exposure of animals and humans to PFAS through contaminated water and foods pose significant threats to public health. To tackle this challenge, this study aimed to develop edible clays that might enhance the binding, detoxification, and elimination of PFAS in the gastrointestinal tract. Montmorillonite clays (CM) were amended with caffeine (CMCAF), curcumin (CMCUR), and riboflavin (CMRIB), and the binding efficacy for a mixture of four PFAS (PFOS, GenX, PFOA and PFBS) was determined. In vitro studies were used to explore adsorption isotherms while computational simulations investigate PFAS mixture, delineate the contribution of each PFAS molecule to clays and determine if amended clays can contribute to enhanced binding of different PFAS in the mixture. In vivo models (Lemna minor and Hydra vulgaris) were used to validate in vitro and in silico studies and establish the safety and effectiveness of these amended clays. The resulting Q_max and K_d values along with the curved shape of the Langmuir plot indicated saturable binding of GenX, PFOA and PFOS to active surfaces of CM and the amended clays. All three clays demonstrated a slightly higher binding capacity for GenX than the parent clay. Furthermore, the simulations elucidated the binding contribution of each PFAS molecule to parent and amended clays as well as predicting how amended clays can contribute to mechanisms of binding of different PFAS in the mixture. The proof-of-concept for the efficacy of the clays was established in Caenorhabditis elegans, Lemna minor and Hydra vulgaris, where the clays (at 1% w/v inclusion) protected against toxicities of the four PFAS controls. This protection could be attributed to PFAS binding to the amended clays and the biological activities of these nutraceuticals (caffeine, riboflavin, and curcumin) including antioxidative, anti-inflammatory and modulatory activities which mitigate the oxidative stress and inflammatory effects of PFAS. These edible toxin binders may be delivered in mixtures as additives in flavored drinking water and food to decrease PFAS exposure.