In vitro degradation and bioactivity of poly(propylene fumarate)/bioactive glass sintered microsphere scaffolds for bone tissue engineering

We developed degradable poly(propylene fumarate)/bioactive glass (PPF/BG) composite scaffolds based on a sintered microsphere technique and investigated the effects of BG content on the characteristics of these composite scaffolds. Immersion in a simulated body fluid (SBF) was used to evaluate the surface reactivity of composite scaffolds. The surface of composite scaffolds was covered with hydroxycarbonate apatite layer after 7 days of immersion. Ion concentration analyses revealed a decrease in P concentration and an increase in Si, Ca, and Sr concentrations in SBF immersed with composite scaffolds during the 3-week period. The Ca and P uptake rates decreased after 4 days of incubation. This coincided with the decrease of the Si release rate. These data lend support to the suggestion that the Si released from the BG content of scaffolds present in the polymer matrix was involved in the formation of the Ca-P layer. The evaluation of the in vitro degradation of composite microspheres revealed that the weight of scaffolds remained relatively constant during the first 3 weeks and then started to decrease slowly, losing 10.5% of their initial mass by week 12. Our results support the concept that these new bioactive, degradable composite scaffolds may be used for bone tissue engineering applications.