Double Layered Microshells Composed of Calcium Phosphate and Poly(Lactic Acid)

摘要

Biodegradable microshells were synthesized by an improvement surfactant-free emulsion solvent evaporation method. The oil in water emulsions composed of the organic phase of poly(lactic acid) in dichloromethane and the aqueous phase including Ca{sup}(2+) ions and PO{sub}4{sup}(3-) ions were firstly cooled down by an ice bath to stabilize emulsification. During the emulsions was returning to room temperature, calcium phosphate was rapidly precipitated at the oil/water interface, which would result in stabilizing the microshell structure on unstable liquid oil droplets. The precipitated hard calcium phosphate shells acted as a framework for poly(lactic acid) deposition by volatilization of dicloromethane. The resulting microshells were approximately 50 - 300 μm in diameter with the wall thickness of 1 - 10 μm. The walls of the microshells had a double-layered structure composed of external walls of calcium phosphate and internal walls of poly(lactic acid). The biodegradable double-layered microshells were expected to be utilized as drug delivery carriers for injectable bone substitute.