Crystallization rules of calcium oxalate crystals in lithogenic urine and in healthy urine in vitro

Preparation, properties, formation mechanisms, and cytotoxicity of calcium oxalate monohydrate with various morphologies

Calcium oxalate monohydrate (COM) crystals with various morphologies, such as elliptical, hexagonal, peanut-like, spherical and flower-like structures with a size of about 10 μm, were prepared through varying the reactant concentration, stirring speed, reaction temperature, and additive.

Effects of low molecular weight organic acids on the immobilization of aqueous Pb(II) using phosphate rock and different crystallized hydroxyapatite

Understanding the effects of low molecular weight organic acids (LMWOAs) on the transformation of Pb(II) to geochemically stable pyromorphite (PY) by apatite materials (AMs), has considerable benefits for risk assessment and remediation strategies for contaminated water and soil. In this study, we systematically investigated the immobilization of Pb(II) from aqueous solution by natural phosphate rock (PR) and different crystallized hydroxyapatite (HAp) in the absence and presence of LMWOAs (oxalic, malic and citric acids). The results indicated that the effectiveness of PR and HAp in immobilizing Pb(II) followed in descending order by HAp2 (the poorly crystallized HAp), HAp1 (the well crystallized HAp) and PR, regardlessof the presence of LMWOAs. The presence of malic and citric acids significantly decreased the immobilizationefficiency of Pb(II) by HAp1 and PR, clarifying the lower adsorption affinities of Pb(II)-organic acid complexes on HAp1 and PR rather than Pb(II) ion. On thecontrary, oxalic acid could markedly enhance the removal of Pb(II) from aqueous solution by HAp1 and PR through the formation of lead oxalate, which was confirmed by FT-IR and XRDanalysis. Results also showed that LMWOAs had little promoting or inhibiting effect on the immobilization of Pb(II) by HAp2. This study suggested that the ubiquity of LMWOAs in natural environments could retard the transformation efficiency of Pb(II) to PY by AMs, especiallyin thepresenceof oxalic acid, and the poorly crystallized HAp2 had great potential to remediate Pb(II)-contaminated water and soil due to its insusceptibility to LMWOAs.

Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method

In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462 cm(-1) (I(COM)), 1473 cm(-1) (I(COD)), 961 cm(-1) (I(HAP)) and 1282 cm(-1) (I(UA)) were used.

FT-Raman spectral analysis of human urinary stones

FT-Raman spectroscopy is the most useful tool for the purpose of bio-medical diagnostics. In the present study, FT-Raman spectral method is used to investigate the chemical composition of urinary calculi. Urinary calculi multi-components such as calcium oxalate, hydroxyl apatite, struvite and uric acid are studied. FT-Raman spectrum has been recorded in the range of 3500-400 cm(-1). Chemical compounds are identified by Raman spectroscopic technique. The quantitative estimations of calcium oxalate monohydrate (COM) 1463 cm(-1), calcium oxalate dehydrate (COD) 1478 cm(-1), hydroxyl apatite 959 cm(-1), struvite 575 cm(-1), uric acid 1283 cm(-1) and oxammite (ammonium oxalate monohydrate) 2129 cm(-1) are calculated using particular peaks of FT-Raman spectrum. The quantitative estimation of human urinary stones suitable for the single calibration curve was performed.

Morphology, particle size distribution, aggregation, and crystal phase of nanocrystallites in the urine of healthy persons and lithogenic patients

BACKGROUND

The first step in urinary stone formation is the nucleation of urinary mineral from supersaturated urine. The formed nuclei then grow or/and aggregate to a pathological size. Thus, the nanocrystallites in urine may be related to the formation of urinary stones.

METHODS

Nanocrystallites with a size of less than 1000 nm in the urine samples of 85 healthy persons and 65 lithogenic patients were comparatively investigated using laser scattering spectroscopy, TEM, and X-ray diffraction.

RESULTS

Most of the nanocrystallites in healthy urine samples were spheroidal, less aggregated, well-dispersed, and with a narrow particle size distribution from about 20 to 350 nm. In contrast, most of the particles in lithogenic urines had sharply angled edges and tips, were aggregated, and had a broad particle size distribution from 1.1 to 1000 nm. More calcium oxalate dihydrate (COD) nanocrystallites were found in healthy urine; however, more calcium oxalate monohydrate (COM) nanocrystallites were found in lithogenic urine.

CONCLUSIONS

The morphology, particle size, aggregation, and crystal phase of nanocrystallites in the urine of lithogenic patients are pronouncedly different from those of healthy persons. The results suggest, in ascending order of importance, that making nanocrystallites rounded, diminishing their size differentiation, and decreasing their aggregation in urine by physical and chemical methods maybe the means to prevent urinary stone formation. The most crucial among the four differences is the crystal phase differential of calcium oxalate (CaOxa). That is, the formation of COD nanocrystallites in urine can be considered as being relatively more favorable in preventing stone formation than the formation of COM nanocrystallites, which are in accord with those found for larger crystallites.