engleski

Induction of crystallization of calcium oxalate dihydrate in micellar solutions of anionic surfactants

Calcium oxalate dihydrate (CaC2O4 . (2+x) H2O ; COD ; x ?0, 5) does not readily crystalluria and kidney stone. In this paper, we review in vitro studies on the factors responsible for its nucleation and growth with special attention given to the role of ionic surfactants. All anionic and cationic surfactants studied, dodecyl ammonium chloride (DDACl) , sodium dodecyl sulfate (SDS) , dioctyl sulphosuccinate (AOT), and sodium cholate (NaC) inhibited crystallization of calcium oxalate hydrates but only the anionic surfactants effectively induced a change in the crystallizing polymorph, i.e. COD crystallized at the expense of calcium oxalate monohydrate (CaC2O4 . H2O ; COM). The proportion of COD in the precipitates abruptly increased above the critical micellar surfactants admicelles (two-dimensional surface aggregates) at the surfaces of growing crystals. Studies of the adsorption of surfactants at the surfaces of prepared COM and COD crystals are in agreement with this hypothesis showing significantly higher adsorption of surfactants at the surfaces at COM as compared to the COD/ solution interface.

biomineralization; calcium oxalate dihydrate; surfactants

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