摘要
The effects of temperature and multifunctional sodium carboxylate additives on the phase composition and morphology of calcium oxalate (CaOxa) crystals grown in silica gel system were systematically investigated using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and Fourier-transform infrared spectra (FT-IR). The sodium carboxylates investigated include: monocarboxylate sodium acetate (NaAc), disodium tartrate (Na2tart), trisodium citrate (Na3cit), and the disodium salt of ethylenediaminetetraacetic acid (Na2edta). The temperature range was from 7°C to 67°C. The crystallization temperature affects the phase compositions, the growth rate, and the morphology of CaOxa. First, the logarithm of the percentage of calcium oxalate dihydrate (COD) formed at a certain temperature (T) is proportional to the reciprocal of temperature (1/T). Second, the weight of CaOxa crystals decreases as decreasing the temperature. At a given temperature, the ability of the sodium carboxylates to induce COD follows the order: Na2edta Na3cit Na2tart NaAc. Third, the multicarboxylates can decrease the surface area of calcium oxalate monohydrate (COM). It makes the edges and tips of COM crystals blunt and oval. All the three changes, an increase of the content of COD, a decrease of the weight of CaOxa crystals, and a decrease of the surface area of COM crystals, can inhibit the formation of CaOxa stones. These results support the clinical use of citrates and may be helpful in elucidating the mechanisms of the formation of CaOxa calculus. Keywords calcium oxalate - sodium carboxylate - gel - urinary calculi - crystallization - biomineralization
The effects of temperature and multifunctional sodium carboxylate additives on the phase composition and morphology of calcium oxalate (CaOxa) crystals grown in silica gel sys-tem were systematically investigated using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and Fourier-transform infrared spectra (FT-IR). The sodium carboxylates in-vestigated include: monocarboxylate sodium acetate (NaAc), disodium tartrate (Na2tart), triso-dium citrate (Na3cit), and the disodium salt of ethylenediaminetetraacetic acid (Na2edta). The temperature range was from 7℃ to 67℃. The crystallization temperature affects the phase compositions, the growth rate, and the morphology of CaOxa. First, the logarithm of the per-centage of calcium oxalate dihydrate (COD) formed at a certain temperature (T) is proportional to the reciprocal of temperature (1/T). Second, the weight of CaOxa crystals decreases as de-creasing the temperature. At a given temperature, the ability of the sodium carboxylates to in-duce COD follows the order: Na2edta > Na3cit > Na2tart >> NaAc. Third, the multicarboxylates can decrease the surface area of calcium oxalate monohydrate (COM). It makes the edges and tips of COM crystals blunt and oval. All the three changes, an increase of the content of COD, a decrease of the weight of CaOxa crystals, and a decrease of the surface area of COM crystals, can inhibit the formation of CaOxa stones. These results support the clinical use of citrates and may be helpful in elucidating the mechanisms of the formation of CaOxa calculus.
基金
This research work was supported by the National Natural Science Foundation of China(Grant No.20031010)
the Key Project of Natural Science Foundation of Guangdong Province(Grant No.013202)
the Key Project of Guangdong Province(Grant No.C31401)
a Fellowship of Alexander yon Humboldt-Stiftung of Germany.
