Stability And Growth Kinetics Of Calcium Oxalate Nanoparticles

Urolithiasis is one of the most common urologic diseases in the world-wide area. However, up to date, there is no ideal method about the prevention of urinary stones and advanced diagnosis. The mechanism for the formation of urinary stones is not yet clearly understood and a number of questions about the physical and chemical factors still remain unanswered. How do these urinary nanocrystallites grow, aggregate, and form into urinary stones ultimately? How to improve the accuracy of detection of nanocrystallites in urine? How the changes of urinary nanocrystallites when urinary concentration increased the calcium oxalate supersaturation? The questions were not yet clearly understood. In this paper, the factors that affect property of calcium oxalate nanocrystallites, the effect of additives on the stabilization of nanocrystallites in urine, the settlement and suspension of nanocrystallites in the storage urine and in retention urine with different supersaturation of calcium oxalate were investigated using Scanning electron microscopy (SEM), Zetasizer Nano-ZS, optical microscopy, X-ray diffraction (XRD) and Ultraviolet-visible absorption (UV-vis). The results can be summarized as follows:Firstly, the calcium oxalate nanocrystallites were prepared by complex precipitation method. The property of calcium oxalate nanocrystallites was discussed. The effects of concentration of crystallites, ultrasonic time, dispersed medium, additives and pH on the properties of COD nanocrystallites were investigated. In addition, the effects of inhibitors (potassium citrate) on the COM and COD nanocrystallites and the differents effects with K3cit between the two kinds of nanocrystallites were discussed. The best dispersion of COD nanocrystallites condition was got; When c(K3cit) was 5×10-3 mol/L, the COM and COD nanocrystallites had smallest size, the most negative Zeta value and best dispersion.Secondly, in order to measure the nanocrystallites in the urine, the urine must be filtered firstly to remove micron impurities. However, as nanocrystal size is small, its surface free energy is higger, resulting in poor reproducibility of detection results. The differents additives (sodium hexametaphosphate, polyethylene glycol 4000 (PEG4000) and PEG6000, sodium dodecyl benzene sulfonate, dodecyl trimethyl ammonium bromides(CTAB)) can make the crystallites stability. The results showed that the CTAB can make the Zeta value seriouly diviate from the true value; the PEG4000, which was added in the urine, can make the best detection results (the best repeatability and similar Zeta value) and make accurate measurement of the size and Zeta value.Thirdly, in filtrated health person urine, the suspended nanocrystallites were grow and aggregated; the sedimentation nanocrystallites were increased with the increased storage time. When the urine and pure water systerm was added in different supersaturations of calcium oxalate respectively, the higher the supersaturation degree of calcium oxalate it was, the more significantly deposition and growth of crystallites had. The crystallites in health person urine was smaller than that in pure water systerm. Even in health person urine, the suspended nanocrystallites were grow and aggregated; the sedimentation nanocrystallites were increased with the increased storage time; so the risk of stone formation was increased obviously.Because there is a lot of calcium oxalate crystallites in urine, this study will help to further investigate the growth of urinary crystallites, clarify the formation mechanism of calcium oxalate stones and the inhibition of K3cit effect on stone formation.