Crystallization of hydroxyapatite under langmuir monolayers

Langmuir monolayer of dihexadecylphosphate (DHP) was employed as a substrate for the growth of hydroxyapatite (HAp) crystals in order to clarify how the crystallization is affected and controlled by the two-dimensionally organized surfactant molecules. Polycrystalline HAp him grown from a supersaturated simulated body fluid under a DHP monolayer was found to be preferentially oriented with (h00) planes parallel to the monolayer. This crystallographic orientation on the monolayer was completely different from those observed in HAp polycrystals grown under a mere solution surface without a monolayer, on Si (100) plane, or on various polymer substrates. Organic surfaces with highly ordered functional groups would in general have potential to catalyze inorganic crystallization in a controlled manner through molecular recognition.