Adsorption sites and mechanisms of phospholipids on the (001) chlorite surface: a theoretical perspective

To better understand the role of minerals in the early stage of life, it’s necessary to analyse the interaction between biomolecules and clay minerals, like clinochlore which is possibly one of the types of minerals present in the Earth's near-surface environment at the time of the origin of life. As a result, it will be crucial for prebiotic chemistry research and organic chemistry development. To this aim, this work explores the interaction between one of the simplest phospholipids and the (001) clinochlore surface. The adsorption process has been investigated by quantum mechanics simulations at the Density Functional Theory (DFT)/B3LYP level of theory, employing the DFT-D3 method for calculating dispersive forces and how those influenced the interaction process. The phospholipid-clinochlore interaction was modelled considering only the brucite-like layer of the phyllosilicate, that is obtained by cleaving the mineral bulk. Two different space group settings of the two-dimensional cell were considered to allow isomorphic substitutions of the Al3+/Mg2+. Both stoichiometric and defective layers have been investigated to characterise the surface electrostatic potential, a property that may influence the interaction between brucite and phospholipid. Given the size of DVPA, 2D supercells of (001) brucite with different surface areas were created to model the adsorption of the phospholipid considering both low and high surface coverages. The results showed that the interaction between the biomolecule and the substrate exhibited a favourable adsorption process across all the models tested and how different geometries and orientations of DVPA are more energetically favourable than others across all tested models. This type of data can be very useful for both biotechnological applications of this substrate and for the research on the origin of life. The results obtained could provide insights into the understanding of mineral-biomolecule interactions for future research.