The degradation properties of the MPs is important to the long-term benefits of the use of the chitosan (CS) based hybrid MPs in bone tissue-engineering, because the degradation kinetics could affect a multitude of processes within the cell, such as cell growth, tissue regeneration, and host response. The aim of this study was to investigate the degradation of solid, hybrid CS microparticles (MPs), CS-10% calcium phosphate (CaHPO4, w/w), and CS-10% calcium carbonate (CaCO3, w/w) MPs in phosphate buffered solution (PBS) over a 30-week period. The hybrid MPs were synthesized by emulsification technique, cross-linked with 64% sodium tripolyphosphate (TPP), purified and air dried overnight. Each sample had 30 mg of MPs was placed in a glass vial with 9 ml of PBS added and then the vial was closed to prevent evaporation. Every week 4 ml of the incubated solution was removed for sample measurement and all samples were replaced with an equivalent amount of fresh medium. The samples were maintained at 37oC under continuous shaking. The hybrid MPs were measured for pH and calcium release, every week in triplicate. At 0, 5, 10, 15, 20, 25, and 30 weeks, surface and bulk morphology were analyzed with a scanning electron microscope (SEM). The degradation data suggested that the hybrid MPs were stable at least up to 25 week and maintain the physiologically relevant pH. Therefore, we can use these hybrid MPs to apply in the bone tissue engineering applications since they do not degrade within a short period.
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