Ab Initio Molecular\nDynamics Simulations of Phosphocholine\nInteractions with a Calcium Oxalate Dihydrate (110) Surface

We use <i>ab initio</i> modeling (CASTEP) to\nhelp elucidate\nthe crystallization phenomena and chemistry behind kidney stone composition\nand formation. To explore the stone formation process, we have constructed\na surface model of calcium oxalate dihydratethe mineral most\ncommonly found in patients with hypercalciuria and modeled stone growth,\nby simulating further calcium oxalate adsorption onto the surface\n(−7.446 eV, −0.065 eV/atom). Furthermore, urine analysis\nof kidney stone patients has previously revealed that their urine\ncontains higher concentrations of phospholipids compared to healthy\nindividuals. Therefore, to investigate the interactions between urinary\nmacromolecules and the growing crystal surfaces at an atomic level,\nwe have performed <i>ab initio</i> molecular dynamics simulations\nof phosphocholine adsorption on calcium oxalate surfaces. We have\nshown that the phosphocholine headgroups become entrapped within the\ngrowing crystal and the lowest energy structures (−18.008 eV,\n−0.0396 eV/atom) are those where the calcium oxalate dihydrate\nsurfaces have become disrupted, with reorganization of their crystallographic\nstructure. Urinary calculi (kidney stones) are a common ailment affecting\naround 10% of the world’s population and resulting in nearly\n90,000 finished consultant episodes (FCE) each year in the United\nKingdom [Hospital\nEpisode Statistics, Admitted Patient CareEngland, 2011–12\nNHS Digital, 2021–2022. https://digital.nhs.uk/data-and-information/publications/statistical/hospital-admitted-patient-care-activity/hospital-episode-statistics-admitted-patient-care-england-2011-12].