Probing Calcium Oxalate Crystallization with Crystal Growth Polymeric Inhibitors. Effect of Polymer Molecular Weight.
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Urolithiasis, the formation of stones in the kidney, urinary bladder, or urinary tract, typically occurs as a result of increased supersaturation of minerals in the kidney. Kidney stones are primarily comprised of calcium oxalate. The main objective of this thesis is to investigate the effects of a synthetic anionic polyelectrolyte, poly(sodium 4-styrene sulfonate) (PSS) on the crystallization kinetics of calcium oxalate in aqueous media. A constant composition potentiostatic technique was employed to determine the nucleation and growth kinetics of calcium oxalate. The constant supersaturation was maintained in the reaction media by continuously replenishing the ions that are consumed in the process of crystal nucleation and/or growth. The role of solution supersaturation and additive properties, the polymer molecular weight and the concentration of polymer charged groups in the crystallization media in particular, was evaluated in both seeded and unseeded experiments. The inhibitory effects of the polymer were compared to the results obtained with citrate, the current pharmacological treatment for kidney stone disease.Higher values of solution supersaturation led to faster nucleation. Induction times were found to be longer in the presence of polymeric additives. Crystal growth rates were seen to increase with increase in supersaturation while they decreased in the presence of polymers. Longer induction times and slower growth were observed in the presence of higher molecular weight polymers as compared to the monomer. A comparison of the inhibition efficiencies of polymer PSS and citrate, revealed that PSS would be required in much lower concentrations and quantities compared to citrate to achieve similar crystal inhibition. Our findings offer a better understanding of the calcium oxalate crystallization kinetics and can aid in the development of effective treatments for kidney stone disease.