3D Organized Macroporous Bioactive Glasses: a Study of Pore Size Effect on Physicochemical Reactivity by Micro-PIXE-RBS

Macroporous biomaterials have attracted much attention during the past decade because of the large range of associated applications (from drug delivery to tissue engineering). The present study focuses on the correlations between macropore size (from 400 to 1500 nm in diameter) and the early steps of biomineralization process and the reactivity in binary (SiO2-CaO) and ternary (SiO2-CaO-P2O5) bioactive glasses. Macrostructured glasses were elaborated by combining sol gel chemistry and an inverse opal method with polystyrene beads colloidal crystals as the template. Macroporosity of these materials has been characterized thanks to thermoporosimetry. The in vitro biomineralization process was studied using particle-induced X-ray emission (PIXE) associated with Rutherford backscattering spectrometry (RBS), which are efficient methods for a highly sensitive multielemental analysis. Thanks to elemental maps of silicon, calcium, and phosphorus obtained at a micrometer scale for various interaction times, we demonstrate that the physicochemical reactions are sensitive to macropore size, even though their kinetic is not modified. This key result is an important step to build tunable biomaterials with a highly reproducible and finely controlled response for an optimized integration in living organisms.