Structure and Photoluminescence properties of europium-doped hydroxyapatite 3-D scaffolds

Full text: Studies of calcium phosphates produce significant technological advances in non-invasive cancer and infection treatment. The applicability of hydroxyapatite (HAP) scaffolds is increasingly used to smart drug delivery systems due their biocompatible and ability to fluorescence probe incorporation. The luminescence probe inclusion, such as Eu³⁺, able a development on traceable biodegradable scaffolds. The literature reports challenges are the europium ion replacement site into hydroxyapatite scaffolds. The present study provides a Eu³⁺ site incorporation analysis and their relation with europium luminescence, as well as, an important new knowledge about three-dimensional HAP scaffolds design by a novel dual-template (corn starch/C16TAB). X-ray absorption spectroscopy techniques (XANES and EXAFS) were used to investigate the valence and the location of the dopant and the results showed that Eu³⁺ ions are incorporated preferentially at the Ca(1) site in the HAP structure with local charge compensating via oxygen interstitial ion and Photoluminescence results suggest that Ca sites symmetry getting even more distorted in samples synthesized with C16TAB as template. Scanning Electron Microscopy (SEM) combined with Ultra-Small Angle X-ray Scattering (USAXS) techniques showed that the porous arrangement is promoted by needle-like shape HAP nanoparticles and that the pore size distributions depend on the order of addition of the calcium and the phosphate ion source solutions during the template preparation stage. The role of the corn starch and the surfactant on the general properties of the three-dimensional (3-D) scaffold formation is discussed comparing structure, photoluminescence, USAXS and SEM results obtained for samples prepared without any of the organic templates and samples with just the C16TAB surfactant. (author)