Surface functionalization of bioactive glasses.

Different cleaning and silanization methods have been applied to bioactive glasses with the aim of covalently bonding bone morphogenetic proteins (BMP-2) to the surface. Several glasses, with different bioactivity index, were cleaned with acidic, basic, or neutral aqueous media to investigate the role of pH in the formation of silanols on glass surfaces of different reactivity. The cleaned glasses were then functionalized using 3-aminopropyl-triethoxysilane (APTS). After the optimization of the silanization procedure, proteins of different complexity were immobilized on the functionalized glasses. To optimize the protein immobilization, a model protein (carnosine) was first used, and the procedure was then used to bind human BMP-2. The glass surfaces were characterized during each step of the treatment by water contact angles and X-ray photoelectron analyses. The APTS functionalization was then used to immobilize bone morphogenetic protein on the bioactive glasses. This result suggested that such a treatment could be successfully used as an efficient alternative to systemic administration of transforming growth factors for the development of local delivery vehicle implants.