New Formulation of FunctionalizedBioactive Glassesto Be Used as Carriers for the Development of pH-Stimuli ResponsiveBiomaterials for Bone Diseases.

The aim of the present contributionis to prepare a functionalizedbioactive glass potentially useful as prosthetic material, but alsoable to release organic molecules in response to a change of the pHenvironment. By this approach it is possible to develop devices whichcan be used for a triggered drug release in response to specific stimuli;this is an attractive research field, in order to avoid either systemicand/or local toxic effects of drugs. In particular, in the presentpaper we report data related to the development of a new formulationof bioactive glasses, their functionalization with organic moleculesto obtain a pH-sensitive bond, their physicochemical characterizationand in vitro bioactivity in simulated biological fluids (SBF), andorganic molecule delivery tests at different pH. The glass functionalization,by means of a covalent reaction, allows us to produce a model of pH-responsivebioactive biomaterial: when it is exposed to specific pH changes,it can favor the release of the organic molecules directly at thetarget site. Cysteamine and 5-aminofluorescein are used as model moleculesto simulate a drug. The materials, before and after the differentfunctionalization steps and in vitro release tests at different pH,have been characterized by means of different experimental techniquessuch as X-ray powder diffraction (XRPD), Raman, FTIR and fluorescencespectroscopies, N2adsorption, thermogravimetric (TGA)and elemental analysis. [ABSTRACT FROM AUTHOR]