A Molecular Rationale for Tailoring the Growth Mechanisms of Biomimetic Calcium Oxalates: Guides to Simplified Proxies of Renal Stones?

We present a combined molecular simulation and experimental study of the mechanisms of calcium oxalate monohydrate formation within a biomimetic matrix. Using a double-diffusion approach to feed calcium and oxalate ions into an agarose gel, we show how selective ion association to different crystal faces may guide the morphogenesis and surface charge of the precipitates. Our analyses rationalize two conceptually different growth mechanisms leading to the aggregation of crystallites in terms of negatively charged needles and positively charged platelets, respectively, whereas embedding organic macromolecules are related to the hosting of counterions. We argue that this reflects a key characteristic of renal stone formation, while benefiting from drastic reduction of system complexity. Hence, the biomimetic setup is suggested for both, ex situ formation of (much simplified) proxies to kidney/urinary stones and steps toward the understanding of growth factors for tailoring inner structure, size, and dispersion in water.