Phase equilibria of estrogenic compounds and water with poly(guluronate): an atomistic study

Estrogenic compounds are an emerging contaminant in wastewater due to human activities, while also being essential chemicals in agricultural practices and biomedical therapies. This contribution presents a systematic investigation of the phase equilibria and associated intermolecular interactions between water, estradiol, estriol, estrone, ethinylestradiol, diethylstilbestrol, mestranol, and progesterone with poly(guluronate). Guluronate is a constituent of the common polysaccharide biopolymer alginate. Molecular dynamics simulations were used to study the cohesive energy density of poly(guluronate) chains, while stochastic molecular simulations were employed to study the mixing energy, coordination numbers, and free energy of water or estrogen + guluronate systems. Phase equilibria were then computed using an extended Flory-Huggins approach coupled with the results of the stochastic atomistic simulations. The results presented herein yield insights into the molecular-level behaviour of these emerging pollutants with this biopolymer, which can assist in future research related to environmental remediation, contaminant detection, and drug release.