Facile Synthesis of Octacalcium Phosphate Nanobelts: Growth Mechanism and Surface Adsorption Properties

Abstract

A thorough understanding of the growth and surface properties of calcium−phosphate nanocrystals is essential for uncovering the mechanism by which their nanostructure interacts with other molecules. Herein, we reported a facile wet-chemical approach using cetyltrimethylammonium bromide (CTAB) for the oriented growth of octacalcium phosphate (OCP) nanobelts with a clean surface. The effect of various synthesis conditions, such as aging time, calcium salt species, CTAB, and/or other additive concentrations, on the growth of OCP nanobelts was examined. The results showed that the morphology of OCP nanobelts from a simple core to complex clusters was easily controlled by increasing aging time and CTAB concentration, whereas the nanobelt growth was heavily inhibited by a minor amount of polyaspartate (i.e., 0.03−0.12 μM). The postadsorption tests indicated the nanobelt surface was highly inert to CTAB, but had affinity to polyaspartate. Furthermore, the adsorption capability of therapeutic biphosphonate on OCP nanobelts and as-hydrolyzed/-thermolyzed HA belt-like counterparts was studied. The mechanism of dandelion-like clusters was proposed, in which the collaborative effect of CTAB vesicles and lamellar templates plays a key role. These results shed light on the underlying growth mechanism and surface adsorption of OCP nanobelt growth, as a potential new guest-species delivery/ adsorption nanomaterial.