Strontium Incorporation on Microspheres of Alginate/β-tricalcium Phosphate as Delivery Matrices

Strontium (Sr) is known to positively affect the mechanism of bone remodelling. Consequently, calcium phosphate bioceramics associated with alginate matrices containing strontium could improve bone regeneration due to gradual strontium release. This work aims to incorporate Sr on microspheres of alginate (ALG)/β-tricalcium phosphate (β-TCP) and evaluates the in vitro release of strontium ions into a buffer solution at pH 4.0 and 7.4. In this study, strontium chloride was employed as a cross-linking agent and Sr source. Energy dispersive spectroscopy (EDS) showed that strontium was incorporated mainly at the surface of the microspheres produced. The in vitro experiments revealed that there is a rapid strontium release up to 24 h at pH 7.4 due to Sr location on microspheres' surface. At pH 4.0 both calcium and strontium were released due to the β-TCP dissolution.