Synthesis and characterization of calcium phosphate macro and mesoporous for drug release systems

Full text: The aim of the present work is the characterization of calcium phosphates, especially hydroxylapatite (HAP - Ca10 (PO₄) 6 (OH)₂) and β-tricalcium phosphate (β-TCP - Ca₃(PO₄)₂) with hierarchical arrangement of pores obtained via organic templates formed by two compounds: cetyltrimethylammonium bromide (C16TAB) surfactant and gelatinized corn starch. The IUPAC-International Union of Pure and Applied Chemistry ranked the pores according to their diameters as: mesopores (2 nm < φ < 0 nm) or macropores (φ > 50 nm). Structures containing hierarchical pores arrangement are useful in many areas of biomaterial engineering such as drug delivery, bone repayments and bone reconstruction. The incorporation of a luminescence probe such as Eu³⁺ in porous HAP and β-TCP increases the applicability of the ending product for drug delivery since the fluorescent probes is already nucleation sites in the inorganic scaffold hosting the drug. The synthesis of pure HAP and β-TCP as well as doped HAP and β-TCP with 6 mol% Eu3+ was also investigate. The samples were structural and morphological characterized via powder X-ray diffraction (XRD), Extended X-ray absorption fine structure of (EXAFS), scanning electron microscopy (SEM) and Small angles X-ray scattering (SAXS). The XRD results indicated that the type of organic template employed promotes variations in the dimensions of the nanoparticles of calcium phosphate in crystalline phases. EXAFS results showed that the local symmetry of the Eu3+ incorporated in hydroxyapatite is consistent with incorporation of Eu3+ in larger scale at the Ca(1) sites of HAP. The SAXS and SEM results indicated that meso and macropores were not obtained on addition of C16TAB alone, whereas the samples produced with the combination of starch and C16TAB have a pore size distribution. (author)