Taranets Y. Effect of organic growth modifiers on the pathogenesis of calcium oxalate monohydrate crystals

Thesis is devoted to the study of the effect of growth modifier molecules (L-Asp, L-Arg, L-Thr amino acids and B1, B6, B12 vitamins) on the nucleation processes, morphology and size of COM crystals. Addition of 20 mM L-Asp and L-Arg to the model COM system at the ratio [Ca2+]/[C2O42-] = 20:1 results in the formation of COM single crystals due to adsorption of amino acid molecules on the growing faces of the crystal. The degree of inhibition of COM crystallization with the addition of L-Asp and L-Arg is found to increase in proportion to the increase in the concentration of amino acids in the solution, and to reache 90.2% and 86.0%, respectively, at a concentration of 20 mM. Thereat, the induction time increases by 10 and 6 times, respectively, in comparison with pure COM. It is shown that the L-Thr amino acid promotes the COM crystallization: the induction time with the addition of 2-20 mM L-Thr decreases by half compared to pure COM. Revealed is for the first time the inhibitory effect of B1, B6, B12 vitamins on the crystallization processes and crystal size of COM. Namely, the degree of inhibition of COM crystal growth is more than 95% at 40-50 mM content of B1 and B6, that almost completely blocks the growth of COM crystals. The addition of vitamin B6 leads to the formation of COM single crystals with a size of 2 microns, which is five times smaller than the size of the crystals grown without additives. The addition of crystallization inhibitors (L-Asp, L-Arg, B1, B6, B12) to the model system is found to reduce the surface energy of COM to 19.8-20.8 mJ/m2 with respect to that of pure COM (22.0 mJ/m2). Key words: calcium oxalate monohydrate, crystal growth, supersaturation, induction time, amino acids, vitamins, the inhibitors of crystallisation.