Solubilidade de fosfatos de calcio em fluido corporeo simulado : biocompatibilidade e propriedades da interface fosfato de calcio/solução

AUTOR(ES)

Sergio Bertazzo

DATA DE PUBLICAÇÃO

2004

RESUMO

The changes that occur at the surface of caIcium phosphates aIong the dissolution process have been considered as one of the key factors in the interaction between living systems and these materials. This is true for osteogenesis as well as for processes that lead to the adsorption and adhesion of cells and proteins to the surface of implants composed of or coated with these phosphates. With a view to improving comprehension of the dissolution process of calcium phosphates, the calcium layer model for the dissolution of calcium phosphates was adapted to treat the variation of the calcium ion concentration in the solution as an experimental parameter. This parameter was determined by a caIcium ion selective electrode. The determination of ns, number of sites available for adsorption at the surface of the phosphates, in Simulated Body Fluid (SBF) for the phosphates studied, indicate that in spite of the difference in medium (pH) where the phosphate is dissolved and the differences existing among the calcium phosphates, the vaIue of ns is similar for aIl the calcium phosphates at the end of the dissolution process, indicating the formation of a similar surface for the different calcium phosphates. In this work, numeric values for the parameters K, related to the adsorption of calcium ions on the surface of the phosphate, and ns vaIues were determined without previous knowledge either of the stoichiometry of the calcium phosphate, or of the pH of the solution used in the dissolution of the materiaIs. This work expands and generalizes the initially proposed model by obtaining the vaIues of ns and K, which help to improve the understanding of the dissolution of calcium phosphates. The conclusions presented in this work are remarkable when compared with the results of the literature, most of which are merely qualitative.

ASSUNTO(S)

ossos

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