Urolithiasis is a very frequent illness found in Argentina; however, stone analysis is not routinely performed. In this work, 86 renal calculi (from cities of Luján and San Antonio de Areco, State of Buenos Aires, Argentina) have been analyzed by infrared and Raman spectroscopies, and the results correlated with the main possible pathological conditions. Calcium oxalate monohydrate (whewellite) and mixtures of calcium oxalate monohydrate and carbonate apatite were the most frequent compounds found in our samples. In order to improve the identification of different phases present in calculi [particularly whewellite and weddellite (calcium oxalate dihydrate)], the second derivative spectra were used. The FTIR spectroscopy together with the second derivative analysis provides the urologist with a good method for calculi component determinations.
Brushite samples doped with Ni(II) in different concentrations, from 5% to 20%, were prepared in aqueous solution at pH ¼ 7 and at two temperatures: 25 and 37 C. The solid samples were characterized by chemical analysis, infrared spectroscopy (FTIR) and x-ray powder diffraction (XRPD). Chemical analysis has shown Ni(II) almost complete incorporation to the solid phase up to 15%. X-ray diffraction patterns have allowed to identify brushite phase with almost no modification of the line breadth and only small shifts of lines positions with increasing Ni(II) incorporation up to 15%. For larger Ni(II) concentration, in solution, a mixture of phases has been detected. Infrared spectra have supported diffraction results. For Ni(II) 20% and over the characteristic bands of HPO 4 2anions tend to vanish, and the typical shaped PO 4 3À bands are observed. These results have allowed to establish that the presence of low levels of Ni in the synthetic process not only helps brushite formation; but, also prevents brushite from apatite conversion and, in addition, preserves brushite crystallinity. According to these findings, it is possible to propose that nickel traces present in the urinary system might be a trigger to brushite stone formation and/or growth, rather than the expected brushite conversion to hydroxyapatite. This outcome would explain the recurrent detection of difficult to treat brushite stones, observed in the last three decades.
The influence of Ni on the crystallinity and thermal stability of calcium-nickel hydroxyapatite solid solutions was studied by x-ray diffraction, infrared and Raman spectroscopy and thermal and chemical analysis. The data reported confirm the assumption that nickel produces a reduction in the degree of crystallinity and a decrease in thermal stability of the synthesized materials. The effect of nickel on calcium Hydroxyapatite (CaHap) crystallization is similar to that exhibited by Mg and Zn. However, in this case, the substituent influence is not limited to the crystal surface and it was possible to determine its incorporation into the CaHap structure.
Abstract-Calcium phosphate materials have been widely used as bone substitute due to its good osteointegration. To improve their osteoinductive and osteoconductive properties several element-substitutions in the calcium phosphate matrices have been explored. In the present work, an overview of biological effects of some substitutions in calcium phosphates is done based on an extensive literature revision. Incorporation of elements such as magnesium, fluoride, manganese, zinc, silicon and strontium enhance the bone induction and conduction of calcium phosphate materials. However, this behavior cannot be attributed only to the elements release. The analyzed literature indicated that element substitutions in low concentrations increase the solubility of the calcium phosphate matrices, increasing their bioactivity. Doped materials result osteoinductive and osteoconductive.
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