Growth Of Monohydrate Crystals Research Articles

The impact of crystal phase transition on the hardness and structure of kidney stones

Calcium oxalate kidney stones, the most prevalent type of kidney stones, undergo a multi-step process of crystal nucleation, growth, aggregation, and secondary transition. The secondary transition has been rather overlooked, and thus, the effects on the disease and the underlying mechanism remain unclear. Here, we show, by periodic micro-CT images of human kidney stones in an ex vivo incubation experiment, that the growth of porous aggregates of calcium oxalate dihydrate (COD) crystals triggers the hardening of the kidney stones that causes difficulty in lithotripsy of kidney stone disease in the secondary transition. This hardening was caused by the internal nucleation and growth of precise calcium oxalate monohydrate (COM) crystals from isolated urine in which the calcium oxalate concentrations decreased by the growth of COD in closed grain boundaries of COD aggregate kidney stones. Reducing the calcium oxalate concentrations in urine is regarded as a typical approach for avoiding the recurrence. However, our results revealed that the decrease of the concentrations in closed microenvironments conversely promotes the transition of the COD aggregates into hard COM aggregates. We anticipate that the suppression of the secondary transition has the potential to manage the deterioration of kidney stone disease.

The inhibitory effects of epigallocatechin-3-gallate on calcium oxalate monohydrate crystal growth, aggregation and crystal-cell adhesion

Epigallocatechin-3-gallate (EGCG), a predominant phytochemical in tea plant, has been reported to prevent kidney stone formation but with vague mechanism. We investigated modulatory effects of EGCG (at 0.1–100 µM) on calcium oxalate monohydrate (COM) crystals at various stages of kidney stone development. EGCG significantly increased crystal size (at 1–100 µM), but decreased crystal number (at 10–100 µM), resulting in unchanged crystal mass and volume. Interestingly, EGCG at 10–100 µM caused morphological change of the crystals from typical monoclinic prismatic to coffee-bean-like shape, which represented atypical/aberrant form of COM as confirmed by attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy. EGCG at all concentrations significantly inhibited crystal growth in a concentration-dependent manner. However, only 100 µM and 10–100 µM of EGCG significantly inhibited crystal aggregation and crystal-cell adhesion, respectively. Immunofluorescence staining (without permeabilization) revealed that surface expression of heat shock protein 90 (HSP90) (a COM crystal receptor) on MDCK renal cells was significantly decreased by 10 µM EGCG, whereas other surface COM receptors (annexin A1, annexin A2, enolase 1 and ezrin) remained unchanged. Immunoblotting showed that 10 µM EGCG did not alter total level of HSP90 in MDCK cells, implicating that its decreased surface expression was due to translocation. Our data provide a piece of evidence explaining mechanism underlying the anti-lithiatic property of EGCG by inhibition of COM crystal growth, aggregation and crystal-cell adhesion via reduced surface expression of HSP90, which is an important COM crystal receptor.

Single crystal growth and characterization of pyroelectric L-arginine dihydrobromide monohydrate (LADB)

The formation and the crystal growth conditions of all compounds from the L-Arg + HBr + H2O system were studied and described. IR spectroscopy method was used to identify the obtained crystals. Solubility was determined by the sequential dissolution of decreasing amounts method at a given temperature. The main difficulty of L-Arginine dihydrobromide monohydrate (LADB) crystal growth is its very high solubility in water. This study however demonstrates that a high-quality single crystal was grown by the SERS method, developed by the authors. The achieved high quality of grown LADB crystal makes it possible to count on its wide application as a pyroelectric crystal. These grown crystals were subjected to a microhardness study. Thermal properties and UV–Vis transmittance spectrum were also investigated. The efficiency of the second harmonic generation of L-arginine halide crystals was measured and compared with that of KDP.

Discovering inhibitor molecules for pathological crystallization of CaOx kidney stones from natural extracts of medical herbs

Ethnopharmacological relevanceKidney stones is one of the common diseases of the urinary system. The primary cause of kidney stone formation is the thermodynamic supersaturation of lithogenic solutes in urine, which desaturates by nucleation, crystal growth and aggregation of minerals and salts, mainly Calcium oxalate (CaOx). One of the potential therapies is to develop drug molecules to inhibit or prevent CaOx crystallization in urine. Traditional Chinese medicines (TCMs) provided an efficient approach for the treatment of kidney stones with a specialized-designed recipe of medicinal herbs. But the action details of these herbs were poorly understood due to their complex components, and whether the effective constituents of herbs have an inhibitory effect on the process of stone formation has not been evaluated. Aim of the studyThis study aims to develop and identify inhibitor substitutes from a library of kidney stone prescriptions in traditional Chinese medicines to prevent pathological kidney stone formation. Materials and methodsAs many as twenty Chinese medicines were extracted and separated into five different polar extracts, the inhibition performance of which on CaOx crystallization was explored by recording and comparing crystallization kinetics. The potential inhibitor molecules in the inhibitory extracts were confirmed by HPLC and their retardation efficacy was evaluated by quantifying nucleation and growth kinetics using colorimetry. Then the inhibitor-COM crystal interactions and specificity were examined by morphology evolution and surface structure analysis. In vitro inhibition performance of inhibitors on crystal growth and attachment of CaOx crystals to human renal epithelial cells were further evaluated by recording the nucleation and adhesive crystal numbers. Results and conclusionWater- and n-butanol- soluble extracts from 20 kinds of herbs show almost 100% inhibition percentage, and the n-butanol extracts was found better than commercial drug citrate. Twenty-one molecule substitutes were identified from these extracts, and among them polyphenols display the best inhibition efficacy to retard CaOx crystallization. The high-throughput colorimetric assay and morphology examinations reveals thirteen out of 21 molecules show inhibition potential and disrupt growth of CaOx monohydrate crystals by interacting with exposed Ca2+ and C2O42− on the (100) and (010) surfaces. Moreover, these inhibitors also display pronounced performance in protecting renal epithelial cells by inhibiting nucleation and adhesion of CaOx crystals to cells, thus reducing stone formation. The structure-performance correlation among 19 screened molecules that inhibitors having pKa<3.5, logD (pH = 6) <0, H-number>0.1 mmol are the best in suppressing CaOx crystallization. Our findings provide a novel solution to design and manufacture inhibitor drugs from Chinese medicines for preventing pathological kidney stones formation.

Inhibition of Calcium Oxalate Formation and Antioxidant Activity of Carboxymethylated Poria cocos Polysaccharides.

Three carboxymethylated Poria cocos polysaccharides (PCP-C1, PCP-C2, and PCP-C3) with -COOH contents of 6.13%, 10.24%, and 16.22%, respectively, were obtained by carboxymethylation of the original polysaccharide (PCP-C0), which has a molecular weight of 4 kDa and a carboxyl (-COOH) content of 2.54%. The structure of the PCP-Cs was characterized by FT-IR, 1H NMR, and 13C NMR spectra. The four PCP-Cs exhibited antioxidant activity, and their ability to scavenge radicals (hydroxyl and DPPH) and chelate ferrous ions was positively correlated with the degree of carboxymethylation. As the content of -COOH groups in the PCP-Cs increases, their ability to regulate the growth of calcium oxalate (CaOx) crystals was enhanced, thus inhibiting the growth of calcium oxalate monohydrate (COM) crystals and inducing the formation of more calcium oxalate dihydrate (COD) crystals. The formed CaOx crystal was more round and blunt, the absolute value of the Zeta potential on the crystal surface increased, and the aggregation between crystals was inhibited. Thermogravimetric analysis curves showed that the proportions of PCP-C0, PCP-C1, PCP-C2, and PCP-C3 incorporated into the crystal were 20.52%, 15.60%, 10.65%, and 9.78%, respectively, in the presence of 0.4 g/L PCP-Cs. PCP-C protection resisted oxidative damages of human kidney proximal tubular epithelial cells (HK-2) caused by oxalate, resulting in increased cell viability and superoxide dismutase activity and decreased reactive oxygen species levels, malondialdehyde content, and 8-hydroxy-deoxyguanosine expression. Hence, PCP-Cs, especially PCP-C3, can inhibit the formation of CaOx crystals and may have the potential to be an alternative antistone drug.

Controlling nucleation and crystal growth during reactive crystallization of monosodium urate monohydrate from simulated synovial fluid by N2 fine bubble injection

To control the nucleation and growth of monosodium urate monohydrate (MSU) crystals, we studied the reactive crystallization of MSU from simulated synovial fluid using the gas–liquid interfaces around N2 fine bubbles as novel crystallization fields. In the regions near the gas–liquid interfaces, local supersaturation is generated because of the accumulation of Na+ resulting from the negative electric charge on the fine bubble surface. Hence, the micronization of MSU crystals is expected to occur via growth suppression through the enhancement of nucleation. N2 fine bubbles were continuously supplied to the simulated synovial fluid with 140 mmol/L-Na+ and 3.6 mmol/L-uric acid using a pressurized dissolution-type fine bubble generator. The injection time of the N2 fine bubbles was varied within 60 min to control the volume density of the fine bubbles. The simulated synovial fluid containing N2 fine bubbles was sampled and sealed on a microscope slide, and the reactive crystallization of MSU was performed by standing operation. When the volume density of fine bubbles was increased, the crystal growth was suppressed because of the increasing effective nuclei number and the decreasing consumption of supersaturation for crystal growth caused by the acceleration of nucleation, which led to the generation of numerous fine crystals of needle-shaped MSU.

Biosynthesis of selenium nanoparticles and their effect on changes in urinary nanocrystallites in calcium oxalate stone formation.

Plant bio constituents have the ability to prepare nanoparticles, and usually, plant polyphenols are tested to reduce sodium selenite to selenium nanoparticles (SeNPs). In this work, we showed the biosynthesis of SeNPs using Ocimum tenuiflorum leaf extract. The as obtained SeNPs were in the size range of 15-20nm and spherical in shape. Also, TEM microscopic images represented the aggregation of crystal structures as extracellular deposits. Moreover, scanning electron microscopy was performed to examine the chemical transition of calcium oxalate (CaC2O4) crystal's shape and structure due to the influence of SeNPs. SeNPs inhibited the aggregation and growth of CaC2O4 monohydrate crystals and hence the prepared SeNPs could have important prospects in medical and pharmaceutical applications as a potential inhibitor of CaC2O4 urinary stones.

Development of nanodispersion-based sildenafil metered-dose inhalers stabilized by poloxamer 188: a potential candidate for the treatment of pulmonary arterial hypertension

Objectives: This study aims to formulate nanodispersion-based sildenafil metered-dose inhalers (MDIs) by using poloxamer 188 (P188) as a stabilizer; to evaluate their stability, aerosol characteristics, cytotoxicity, and inflammatory effects; and to investigate the effects of P188 on stability and aerosol characteristics of the MDIs.Methods: The stability and uniformity of the formulations were evaluated by high-performance liquid chromatography method. The aerosol characteristics were evaluated by the Next Generation Impactor. The cytotoxicity and inflammatory effects on respiratory epithelial cells and alveolar macrophages were evaluated by MTT assay and TNF-α, IL-1β, and NO assay, respectively.Results: The optimal formulation was stable and well-uniform after 6 months. The fine particle fraction and mass median aerodynamic diameter (MMAD) of the formulation were 61.9% ± 2.5% and 1.69 ± 0.06 µm, respectively. The formulation was found to be nontoxic to respiratory epithelial cells and did not induce the inflammatory responses of alveolar macrophages. A positive correlation between P188 concentration and MMAD of the MDIs was observed. P188 possesses an ability to prevent the growth of sildenafil citrate monohydrate crystals in the formulations.Conclusions: The findings provided a basis for the development of sildenafil MDI as a potential candidate for the treatment of pulmonary arterial hypertension.

Solid dispersions of Myricetin with enhanced solubility: Formulation, characterization and crystal structure of stability-impeding Myricetin monohydrate crystals

Three solid dispersion forms of Myricetin combined with the Polyvinylpyrrolidone were successfully prepared by spray drying method, and characterized by X-ray powder diffraction, thermal analysis, infrared spectroscopy and optical microscopy. Zeta potential measurements provided indications on solid dispersions stability in aqueous suspension related to their storage at elevated temperature and relative humidity, which depends on the Myricetin load. By increase of Myricetin load, the stability of the solid dispersion is impeded due to growth of Myricetin monohydrate crystals. The amorphous dispersions with 10% and 50% Myricetin load are stable and, compared to pure Myricetin, their aqueous solubility is enhanced by a factor of 47 and 13, respectively. The dispersion with 80% Myricetin load is unstable on storage, and this behavior acts in conjunction with the development of Myricetin monohydrate crystals. Single-crystal X-ray diffraction results obtained for Myricetin monohydrate reveal a structure of an infinite 2D network of hydrogen-bonded molecules involving all six hydroxyl groups of Myricetin. The water molecules are positioned in between the infinite chains, and contribute via H-bonds to robust crystal packing. The calculated needle-like morphology of monohydrate form is in agreement with the optical microscopy results. The study shows that the solid amorphous dispersions with up to 50% Myricetin load are a viable option for achieving substantial solubility improvement of Myricetin, and supports their potential use in pharmaceutical applications.

Growth and characterization of pure and barium doped calcium oxalate monohydrate crystals

Growth and characterization of pure and barium doped calcium oxalate monohydrate crystals

L-Threonine Amino Acid as a Promoter of the Growth of Pathogenic Calcium Oxalate Monohydrate Crystals

Investigated is the effect of L-threonine (L-thr) amino acid on the growth of pathogenic calcium oxalate monohydrate (СОМ) crystals. It is found that L-thr molecules inhibit the growth of COM crystals and prevent their aggregation. Additions of 2-4 mM L-threonine in the investigated system decreases the crystal size (5-6 μm) in comparison with that of СОМ crystals without additives (9 μm). Increase of L-thr concentration in the solution up to 8-20 mM does not lead to further decrease of the crystal size.

Caffeine prevents kidney stone formation by translocation of apical surface annexin A1 crystal-binding protein into cytoplasm: In vitro evidence.

Recent large 3 cohorts have shown that caffeinated beverage consumption was associated with lower risk of kidney stone disease. However, its protective mechanisms remained unknown and had not been previously investigated. We thus evaluated protective effects of caffeine (1 μM–10 mM) on calcium oxalate monohydrate (COM) kidney stone formation, using crystallization, crystal growth, cell-crystal adhesion, Western blotting, and immunofluorescence assays. The results showed that caffeine reduced crystal number but, on the other hand, increased crystal size, resulting in unchanged crystal mass, consistent with crystal growth that was not affected by caffeine. However, caffeine significantly decreased crystal-binding capacity of MDCK renal tubular cells in a dose-dependent manner. Western blotting and immunofluorescence study of COM crystal-binding proteins revealed significantly decreased level of annexin A1 on apical surface and its translocation into cytoplasm of the caffeine-treated cells, but no significant changes in other COM crystal-binding proteins (annexin A2, α-enolase, HSP70, and HSP90) were observed. Moreover, caffeine decreased intracellular [Ca2+] but increased [Ca2+] secretory index. Taken together, our findings showed an in vitro evidence of the protective mechanism of caffeine against kidney stone formation via translocation of annexin A1 from apical surface into cytoplasm to reduce the crystal-binding capacity of renal tubular epithelial cells.

Peptides of Matrix Gla Protein Inhibit Nucleation and Growth of Hydroxyapatite and Calcium Oxalate Monohydrate Crystals

Matrix Gla protein (MGP) is a phosphorylated and γ-carboxylated protein that has been shown to prevent the deposition of hydroxyapatite crystals in the walls of blood vessels. MGP is also expressed in kidney and may inhibit the formation of kidney stones, which mainly consist of another crystalline phase, calcium oxalate monohydrate. To determine the mechanism by which MGP prevents soft-tissue calcification, we have synthesized peptides corresponding to the phosphorylated and γ-carboxylated sequences of human MGP in both post-translationally modified and non-modified forms. The effects of these peptides on hydroxyapatite formation and calcium oxalate crystallization were quantified using dynamic light scattering and scanning electron microscopy, respectively. Peptides YGlapS (MGP1-14: YγEpSHEpSMEpSYELNP), YEpS (YEpSHEpSMEpSYELNP), YGlaS (YγESHESMESYELNP) and SK-Gla (MGP43-56: SKPVHγELNRγEACDD) inhibited formation of hydroxyapatite in order of potency YGlapS > YEpS > YGlaS > SK-Gla. The effects of YGlapS, YEpS and YGlaS on hydroxyapatite formation were on both crystal nucleation and growth; the effect of SK-Gla was on nucleation. YGlapS and YEpS significantly inhibited the growth of calcium oxalate monohydrate crystals, while simultaneously promoting the formation of calcium oxalate dihydrate. The effects of these phosphopeptides on calcium oxalate monohydrate formation were on growth of crystals rather than nucleation. We have shown that the use of dynamic light scattering allows inhibitors of hydroxyapatite nucleation and growth to be distinguished. We have also demonstrated for the first time that MGP peptides inhibit the formation of calcium oxalate monohydrate. Based on the latter finding, we propose that MGP function not only to prevent blood-vessel calcification but also to inhibit stone formation in kidney.

Melamine-promoted crystal growth of calcium oxalate monohydrate from calcium nitrate and oxalic acid

The influence of melamine with different concentrations on the spontaneous batch crystallization of calcium oxalate monohydrate was investigated. The self-assembly of different sizes of calcium oxalate monohydrate crystals was achieved by layering a mixture of ethanol–water solutions of calcium nitrate and oxalic acid with different concentrations of melamine at room temperature. The presence of melamine accelerated the growth of large-sized calcium oxalate crystals but inhibited the total weight of the crystals. Precise EDX, IR and powder X-ray diffraction analyses of the product permitted its chemical composition to be determined. Such analyses lead to the finding that the reactions produced calcium oxalate monohydrate, that their average size increases from 1.5 × 10− 3 to 4.4 × 10− 3 cm3, while the total weight decreases from 3.6 to 1.5 mg with an increase of the amount of melamine. This finding is particularly significant for the renal and kidney failure due to the growth of large calcium oxalate monohydrate crystals in the presence of melamine.

Spectral, optical, and thermal studies of pure and Zn(II)-doped l-histidine hydrochloride monohydrate (LHHC) crystals

The influence of doping the transition metal Zn(II) on the growth, spectral, optical, and thermal properties of l-histidine hydrochloride monohydrate (LHHC) crystals grown by slow solvent evaporation method has been investigated. Structural characterizations of the grown crystals were carried out by single crystal X-ray diffraction analysis and it shows slight structural changes as a result of doping. The FT-IR spectral study reveals the presence of various functional groups and confirms the slight distortion of the structure of the crystals due to doping. The energy dispersive X-ray analysis reveals the incorporation of Zn(II) in the crystalline matrix of LHHC crystal. The UV–Vis spectral study was carried out to analyze the optical transmittance of the grown crystals and found that the transmittance is very high in the visible and UV regions for both pure and doped crystals. The second harmonic generation (SHG) for the grown crystals was confirmed by Nd:YAG laser. The scanning electron microscopy reveals the presence of defect centers and crystal voids. The thermal stability and purity of the grown crystals were analyzed by thermogravimetry, differential thermal analysis, and differential scanning calorimetry techniques.

Citrate Modulates Calcium Oxalate Crystal Growth by Face-Specific Interactions

Because of its ability to inhibit the growth of calcium oxalate monohydrate (COM) crystals, citrate plays an important role in preventing the formation of kidney stones. To determine the mechanism of inhibition, we studied the citrate-COM interaction using a combination of microscopic and simulation techniques. Using scanning confocal interference microscopy, we found that addition of citrate preferentially inhibits crystal growth in <100> and, to a lesser extent, <001> directions, suggesting that citrate adsorbs to the faces of COM in the order {100} > {121} > {010}. Scanning electron microscopy showed that the resulting crystals are plate shaped, with large {100} faces and rounded ends. Molecular-dynamics simulations predicted, however, that citrate interacts with the faces of COM in a different order, i.e. {100} > {010} > {121}. Our simulations showed that citrate molecules align with the rows of Ca²⁺ ions on the {010} face but do not form close contacts, presumably because of electrostatic repulsion by the carboxylate groups that project from the Ca²⁺-rich plane. We propose that this weak interaction is responsible for citrate’s limited inhibition of COM growth in <010> directions. Overall, these findings indicate that electrostatic interactions with the Ca²⁺-rich faces of COM crystals are responsible for the growth-modulating properties of citrate.

Red Blood Cell Membrane Fragments but Not Intact Red Blood Cells Promote Calcium Oxalate Monohydrate Crystal Growth and Aggregation

Cell membranes are thought to promote calcium oxalate kidney stone formation but to our knowledge the modulating effect of red blood cell membranes on calcium oxalate crystals has not been previously investigated. Thus, we examined the effects of red blood cell membrane fragments on calcium oxalate monohydrate and calcium oxalate dihydrate crystal growth and aggregation. Calcium oxalate monohydrate and calcium oxalate dihydrate crystals were treated with red blood cell membrane fragments or intact red blood cells from a healthy donor. Phase contrast microscopy was performed to evaluate crystal morphology and aggregation. We used ImageMaster 2D Platinum software to evaluate crystal size and spectrophotometric oxalate depletion assay to monitor crystal growth. Red blood cell membrane fragments had significant promoting activity on calcium oxalate monohydrate crystal growth with an approximately 75% increase in size and aggregation with an approximately 2.5-fold increase in aggregate number compared to the control without membrane fragments or cells. Approximately 50% of calcium oxalate monohydrate crystals were adhered by red blood cell membrane fragments. Intact red blood cells had no significant effect on calcium oxalate monohydrate crystal growth or aggregation but they could transform calcium oxalate monohydrate to calcium oxalate dihydrate crystals. Red blood cell membrane fragments and intact red blood cells had no effect on calcium oxalate dihydrate crystals. The promoting activity of red blood cell membrane fragments on calcium oxalate monohydrate crystal growth was successfully confirmed by spectrophotometric oxalate depletion assay. To our knowledge our data provide the first direct evidence that red blood cell membrane fragments are a promoting factor for calcium oxalate monohydrate crystal growth and aggregation. Thus, they may aggravate calcium oxalate stone formation.

In vitro evaluation of Terminalia arjuna on calcium phosphate and calcium oxalate crystallization

Urinary stones are one of the oldest and the most common afflictions in humans. This disease has tormented humans since the earliest records of civilization. Ten percent of men and 3 % of women have a stone during their adult lives. Calcium containing stones are the most common comprising about 75 % of all urinary calculi, which may be in the form of pure calcium oxalate (50 %) or calcium phosphate (5 %) or a mixture of both (45 %). A number of plants have been mentioned in the Indian ayurvedic system, which plays a vital role in the inhibition of kidney stones. In the present study, the inhibitory potency of crude extracts or fractions of successive solvent extractions of Terminalia arjuna bark was evaluated on various stages of formation of calcium phosphate and on the growth of calcium oxalate monohydrate crystals in vitro. Results obtained indicated that Terminalia arjuna bark has the potential to inhibit the formation of both calcium phosphate and calcium oxalate crystals in vitro. Butanol fraction of Terminalia arjuna extract was the most effective in inhibiting formation of calcium phosphate and calcium oxalate crystals in vitro.

The effect of Tamm-Horsfall Mucoprotein on the nucleation, growth and aggregation of calcium oxalate monohydrate crystals in vitro

Objective To determine the effect of Tamm-Horsfall Mucoprotein (THM) on the nucleation, growth and aggregation of calcium oxalate monohydrate crystals (COM) in vitro. Methods THM was isolated from normal individuals according to the method of Tamm and Horsfall with a little modification. The concentration of calcium and the amount of COM crystals were determined in the artificial urine and seed crystal system with 0,10,50,100 mg/L THM. Results Under the concentrations of THM being 0,10,50,100 mg/L,the reductions of the concentration of calcium were 0.81,0.57,0.51,0.96 mmol/L; the amounts of nucleation were 3. 20 × 10~4,2. 32×x 10~4 ,1. 83× 10~4, 2. 85×10~4; the growth rate was 53.9% ,48.7% ,34.6% ,19. 8% ;the aggregation rate was 33. 2% ,11.7% ,9.4% ,and 66. 2% respectively. There was significant differences,P<0. 01. Conclusion THM could prevent the calcium oxalate crystals from nucleating,growing and aggregating with the physiological concentration range,but when the concentration of THM got a top limit of the physiological concentration,THM became a promoter of nucleating and aggregating of calcium oxalate crystals. Key words: Calcium oxalate; Mucoprotein; Growth; Aggregation

Inhibition of the crystal growth and aggregation of calcium oxalate by elemental selenium nanoparticles

Chemical modulation of calcium oxalate (CaC 2O 4) crystals morphologies by elemental selenium nanoparticles (nanoSe 0) was investigated with scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectrometry (FTIR), and X-ray diffraction (XRD) analysis. The coordination between nanoSe 0 and C 2O 4 2− had great effect on the formation of CaC 2O 4 crystals. NanoSe 0 inhibited the growth of calcium oxalate monohydrate (COM) crystals, prevented the aggregation of COM crystals and induced the formation of the spherical calcium oxalate dihydrate (COD) crystals containing selenium, which are the thermodynamically less stable phase and has a weaker affinity to the cell membranes than COM crystals. The inhibition of the crystal growth and aggregation of CaC 2O 4 crystals by nanoSe 0 displayed concentration effects.