Fabrication of double-walled microspheres for the sustained release of doxorubicin

Double-walled microspheres with poly(L-lactic acid) shells and poly(DL-lactic-co-glycolic acid) cores were fabricated using solvent evaporation technique which involves the phase separation phenomenon of a binary composite of these two polymers. Doxorubicin, a hydrophilic drug, was entrapped within the core of these double-walled microspheres with different core-shell thicknesses and compositions to investigate the in vitro release on this class of microspheres. Microspheres of different size ranging from 50 to 300 μm were also fabricated to investigate whether this method is suitable for fabricating small particles for intramuscular injection applications, and their phase separation and surface morphology were examined by differential scanning calorimetry, scanning electron microscopy, and optical microscopy.