Inhibition of hydroxyapatite crystal growth by substituted titanocenes

This paper reports a physicochemical investigation of the effect of titanoc enes on hydroxyapatite crystallization in vitro. The experimental condition s resemble the physiological, at sustained supersaturation employing the co nstant composition method. All titanocene dihalides were found to inhibit c rystal growth of hydroxyapatite, possibly through adsorption of the chlorid e hydrolysis products on the active growth sites. It is suggested that the growth mechanism is probably surface-diffusion-controlled spiral growth. To explain the inhibiting activity of the titanocenes, the relation of the or ganometallic compound stereochemistry and the crystal surface characteristi cs is extensively discussed.