Tunable release of proteins with polymer-inorganic nanocomposite microspheres

Polymer-inorganic nanocomposite microspheres were synthesized by a simple solid-in-oil-in-water emulsion technique, to provide sustained protein release with tunable gradient and delayed protein release with tunable lag time. The sustained protein release formulation included systematically modulated gradient of the release profile, by changing variables that affect polymer degradation. The results indicate that within the core/shell structures, proteins are released through the degradation of poly(α-hydroxy acids) (PLGA) core, which results in the dissolution of calcium phosphate and the release of preadsorbed proteins within the core. The delays in protein release is shortened to 2 and 4 weeks when 7 kDa PLGA and a mixture of 7 and 24 kDa PLGA is used. Microspheres prepared with 84 kDa PLGA and calcium phosphate are able to sustain the release of BMP-2 for 7 weeks in a linear profile.