Despite some their high biocompatibility, phosphate glasses, especially binary ones, exhibit poor stabilities in ambient temperature and humidity because they are very hygroscopic. The stability test in air and phosphate buffer saline (PBS) solution monitored by PXRD demonstrate that the composite materials alone were more stable than the ball milled inorganic glass (Fig. ). The presence of ZIF-8 in the composite prevents the recrystallization of the inorganic glass, and increases stability against dissolution in PBS (Fig. ).