Micro PIXE-RBS for the study of Sr release at bioactive glass scaffolds/biological medium interface

Strontium is a very interesting element in bone regeneration as it can promote bone formation and limit bone resorption. Bone tissue engineering has a very high potential as a method for bone healing and it requires a 3D macroporous scaffold to serve as a support for cell growth. In that purpose, strontium containing bioactive glass foams made with the sol-gel foaming process are very promising scaffolds as they combine the high bioactivity of bioactive glasses, the beneficial effects of strontium on bone growth and a structure that would allow cell adhesion, cell invasion and vascularization. This paper reports the synthesis of such a material and its in vitro bioactivity study. The release of strontium ions from the material to the biological medium occurs quickly, as shown by ICP-AES results, with the delivery of quantities of Sr ions that should be adequate for bone regeneration. Ion microbeam techniques evidence a very specific behavior of strontium: it is rapidly removed from the inner part of the material but remains in the calcium phosphate layer that is deposited on the surface of the foam pores. It reveals the particular behavior of glass foams compared to other materials suitable for implantation like glass powders of same composition and highlights the interest of ion microbeam techniques in the study of strontium-containing bioactive glass scaffolds.