Investigation of the impact of catechol on the fluidity of lipid monolayers

In recent years, water pollution has become a critical issue due to population growth and rapid industrialization, with profound consequences for both environmental and public health. Among the key contributors are phenolic compounds, including bisphenol A, catechol, hydroquinone, and resorcinol, which are classified as priority pollutants. These substances exert harmful effects even at low concentrations, driving increasing research efforts focused on understanding their molecular interactions, monitoring their occurrence in wastewater, and developing sustainable strategies for their detection and removal. In particular, catechol is extensively used in a wide range of industrial processes, yet its cellular effects and mechanisms of action remain poorly characterized. To address this gap, lipid monolayers were used as membrane models, for investigating specific interactions with external agents at the molecular level. Two systems were designed to evaluate the role of physical phase heterogeneity: one in a pure liquid-condensed phase and another exhibiting a coexistence between liquid-condensed and liquid-expanded phases. The effects of catechol exposure were assessed through compressibility measurements (π-A isotherms) and Atomic Force Microscopy (AFM) imaging. The results demonstrate that catechol induces marked alterations in the lipid monolayer, increasing disorder within the liquid-condensed phase and reducing its relative proportion in favour of the liquid-expanded phase. Such perturbations in lipid phase organization suggest that catechol may compromise membrane functionality, with potential implications for essential biological processes and disease mechanisms. These findings provide a promising basis for further investigations into the mechanisms underlying catechol-membrane interactions.