Biomimetic Carbonate-Hydroxyapatite Nanocrystals Prepared by Vapor Diffusion (original) (raw)

2010, Advanced Engineering Materials

Hydroxyapatite (HA) [Ca 5 (PO 4) 3 OH] is the main mineral constituent of mineralized tissues like bones and teeth, and there is great interest in understanding the physical mechanisms that underlie its growth, dissolution and phase stability. [1-3] Moreover, it has important biological applications, including osteologic implant coatings, grafts, scaffolds, and bone cavity fillings and vehicles for drug, protein, and gene delivery. [4-7] HA can be synthesized by many chemical-processing routes including solid-state reaction, co-precipitation, sol-gel synthesis, pyrolysis of aerosols, microemulsion, hydrothermal reaction, microwave precipitation, etc. [8-13] Dimensions, morphology, crystallinity degree, and surface properties represent the physico-chemical features which should be tailored in synthetic HA crystals for optimizing their specific biomedical applications. [14] The mineral phase of bone and dentine is constituted of HA crystals with length of about 100 nm, width of 20-30 nm and thickness of 3-6 nm and having low crystallinity degree, crystalline surface disorder, and non-stoichiometric composition especially for the presence of carbonate ions in the crystal lattice. [15] Synthetic biomimetic calcium phosphates need to be prepared with similar morphology, dimensions, structural, and chemical characteristics of biological ones. In fact, the excellent biological properties of HA crystals, such as the lack of toxicity, inflammatory, and immunitary responses, and high bioresorbability can be significantly increased by improving their biomimetism. [16]