Effect of Cationic Surfactant Micelles on Hydroxyapatite Nanocrystal Formation: An Investigation into the Inorganic–Organic Interfacial Interactions

To clarify hydroxyapatite (HAp) nanocrystal formation based on the interfacial interactions with organic molecules is important for controlling the dispersion states/shapes of HAp and understanding the biomineralization mechanism. In this study, the effects of cetyltrimethylammonium bromide (CTAB) micelles on the HAp nanocrystal formation process were investigated through both the morphosynthesis technique and the molecular orbital calculations. The HAp nanocrystals synthesized in the presence of CTAB exhibited a controlled rod-like shape and subsequently grew up by a thermal treatment to be larger-sized nanocrystals at a well-dispersed state. It was also found that the CTAB micelles strained and disordered at the higher temperature effectively induced heterogeneous nucleation to initiate the nucleation/growth processes. In contrast, HAp nanocrystals synthesized without CTAB exhibited irregular-shaped and aggregated nanocrystals, which are due to dominantly occurring homogeneous nucleation. According to t...