Modifications of silicate bioglass synthesis and composition for in vitro dissolution control: Static and dynamic assessment

A set of fifteen calcium-phosphate-silicate glass samples, varying in alkali, magnesium, silicon, and nitrogen content, was prepared, and their structural, thermal, and in vitro dissolution properties were analyzed. Infrared spectroscopy showed a high degree of depolymerization of the silicate network consisting mainly of Q² and Q³ units. Thermal analysis showed that the silicon content primarily affects both the glass transition temperature and the thermal stability of the glasses. In vitro dissolution studies were conducted both in static and dynamic modes in phosphate-buffered saline. Greater weight loss was observed for materials tested in the dynamic mode than in the static mode. Ion concentration profiles determined for PBS after immersing the glasses showed the release of sodium and calcium into solutions. Subsequent studies, conducted using scanning electron microscopy, X-ray diffraction, and infrared spectroscopy showed the formation of an amorphous or crystalline layer of calcium phosphates, most likely hydroxyapatite.