Calcium phosphates (CAPs) can be produced from either biologically sourced materials or mineral deposits. The raw materials impart unique properties to the CAPs due to innate trace amounts of elements that affect the crystal structure, morphology and stoichiometry. Using calcium carbonate (CaCO₃) precursors derived from fossilized calcareous marine sediments (FCMSs), we have synthesized a novel class of CAP biomaterials, termed fm-CaPs, with defined Ca/P molar ratios of 1.4 and 1.7 using a wet synthesis method. Compared with commercially available CAP biomaterials, such as hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP), fm-CaP1.7 had a biphasic composition consisting of an HA phase (in a hexagonal system) and a β-TCP phase (in a rhombohedral crystalline system), which is desirable for the current design of bone substitutes, whereas fm-CaP1.4 consisted of an HA phase and a beta-dicalcium pyrophosphate phase (in a tetragonal system). These bioceramics exhibited a fringe structure of regular crystallographic orientation with well-ordered mesoporous channels. The FCMS raw material imparted trace amounts of silicon (Si), strontium (Sr) and zinc (Zn) to fm-CaPs; these are elements that are important for bone formation. The cyto-compatibility of these biomaterials and their effects on cellular activity were evaluated using osteoblast cells. Cell proliferation assays revealed no signs of cytotoxicity, whereas cells growth was equal to or better than HA and β-TCP controls. The SEM analysis of the cell and material interactions showed good cell spreading on the fm-CaP materials that was comparable to β-TCP and in vitro assays suggested robust osteogenic differentiation, as seen by increased mineralization (alizarin red) and upregulation of osteogenic gene expression. Our results indicate that fm-CaP1.7, in particular, has chemical, physical and morphological properties that make this material suitable for applications that promote bone tissue regeneration.

Nanostructured calcium phosphate and biphasic calcium phosphates have been studied and stand out as biomaterials for bone regeneration. This is due to the fact that thesebiomaterials present bioactivity and morphological, chemical and crystallographic similarities to the bone apatite. The aim of the present work has been the synthesis and characterization of two calcium phosphates with Ca/P=1.5 e 1.67 as molar ratio. These were synthesized through the chemical wet process. After synthesis, the hydrated calcium phosphate powders were subsequently calcined at temperatures of 900°C/2h providing b-calcium phosphate (b-TCP) and hydroxyapatite (HA) powders. These powders were used to elaborate the biphasic powders in the wt.% ratios HA/b-TCP as follows: 80/20, 20/80, 70/30 and 30/70. The method used for the elaboration of the b-tricalcium phosphate nanostructured powder, hydroxyapatite and biphasic compositions was the attrition milling. The nanostructured powders obtained were characterized by the scanning electron microscopy technique, X-ray diffractometry. Infrared spectroscopy and Specific surface using BET model

The present research paper centers on physicochemical characterization of six nanostructured alloplastic bone substitutes developed at Santa Catarina State University (UDESC Brazil). In addition to identifying the main phases, the focus was to measure the morphological and microstructural features, which are believed to be crucial for controlling and guiding biological and molecular events. The studied samples exhibited rounded granules measuring 200μm 10(PO₄)₆(OH)₂] was found as main phase for HAp, BCP and HAp/Al₂O₃ biomaterials. For HAp/TiO2n, HAp/SiO₂n and β-TCP, the major phase was beta tricalcium phosphate [Ca₃(PO₄)₂-β]. The results demonstrate that the presence of a second phase of nanometer order, at a hydroxyapatite bioceramic matrix, may modify the surface diffusion of the grains and the phase transformation kinetics of hydroxyapatite and beta tricalcium phosphate at temperatures up to 1100°C.