Preparation And Growth Kinetices 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 pathogeny for 80%of stone formers was not clearly understood.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 microcrystals grow,aggregate,attach to the renal tubule cell membranes,and form into urinary stones ultimately? What differentiation exists of the number and size of the nanocrystallites between the urines in healthy persons and in stone patients? What differentiation exists of dynamic process of the nanocrystallites between the urines in healthy persons and in stone patients? The questions were not yet clearly understood.In this paper,the optimal preparation condition of CaOxa nanoparticles was investigated using Transmission electron microscopy(TEM),Scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared resonance (FTIR),Zetasizer Nano-ZS(Malvem Instruments,U.K.) and Ultraviolet-visible absorption (UV-vis).Its interaction with the urine inhibitor was compared.And the grown mechanism of COM and COD in pure aquatic system was also discussed.The results can be summarized as follows:Firstly,COD nanoparticles with an average size of about 150-250 nm were prepared by complex precipitation method using K₂C₂O₄ and CaCl₂ as raw materials,NTA as complexing agent and a water solution as the reaction medium.The effects of initial reactant concentrations, pH in reaction system and dispersion media etc.on morphology and size of the nanoparticles were discussed.The results indicated that the prepared sample was calcium oxalate dihydrate (COD) and the morphology of the CaOxa particles was typical tetragonal bipyramid.The optimal preparation condition for nano CaOxa was as follows:the initial concentrations of three reactants were 0.1 mol/L respectively,pH=4 and T=35℃.The effect of the standing time, concentration of CaOxa suspension and the dispersion media on the stability of nano-COD was discussed.The formation mechanism of nano-COD was discussed.Secondly,COM nanoparticles with an average size of about 250-400 nm were prepared by complex precipitation method.The difference of chondroitin sulfate A and sodium citrate interaction with COM and COD were compared.The results indicated that the nano-COD has good dispersion in chondroitin sulfate A solution of different concentration and sodium citrate solution of low concentration.The quantum size effects could be seen in ultraviolet spectra. However,COM has poor dispersion and easily aggregated in solution.The UV-vis absorption peak was not obvious.Thirdly,the difference of crystal grown between COM and COD were investigated in pure aquatic system.The results indicated that COD have all been converted to COM in the third day. With the increase of growth time,the intensity of the diffraction peak of((?)01) face was strengthened of COM crystals.The morphology of COM crystals in pure aquatic system are rectangle and irregular diamond.But the morphology of COD crystals changed from tetragonal bipyramid to hexagon in pure aquatic system.The growth of COD crystals has been the growth of control in pure aquatic system.The size of crystal increased with the increase of crystallization time.According to the theoretical derivation and growth model,the growth mechanism of nano-COD in pure aquatic system was given.The results in this study may provide new clues to investigate the formation mechanism of urinary stones.