Controlling protein release from scaffolds using polymer blends and composites

We report the development of three protein loaded polymer blend and composite materials that modify the release kinetics of the protein from poly(dl-lactic acid) (PdlLA) scaffolds. PdlLA has been combined with either poly(ethylene glycol) (PEG), poly(caprolactone) (PCL) microparticles or calcium alginate fibres using supercritical CO2 (scCO2) processing to form single and dual protein release scaffolds. PdlLA was blended with the hydrophilic polymer PEG using scCO2 to increase the water uptake of the resultant scaffold and modify the release kinetics of an encapsulated protein. This was demonstrated by the more rapid release of the protein when compared to the release rate from PdlLA only scaffolds. For the PdlLA/alginate scaffolds, the protein loaded alginate fibres were processed into porous protein loaded PdlLA scaffolds using scCO2 to produce dual release kinetics from the scaffolds. Protein release from the hydrophilic alginate fibres was more rapid in the initial stages, complementing the slower release from the slower degrading PdlLA scaffolds. In contrast, when protein loaded PCL particles were loaded into PdlLA scaffolds, the rate of protein release was retarded from the slow degrading PCL phase.