Novel solvent-free methods for fabrication of nano- and microsphere drug delivery systems from functional biodegradable polymers

Cholic acid functionalized branched poly-epsilon-caprolactones with different molecular weights were synthesized through the ring-opening polymerization of epsilon-caprolactone initiated by cholic acid with hydroxyl groups. On the basis of the specific physicochemical properties of the functional branched poly-epsilon-caprolactones, nano- and microsphere drug delivery systems were fabricated through a melting ultrasonic dispersion method and a melting emulsion method, respectively. Both methods did not involve toxic organic solvents. Using these very rapid and convenient methods, the drug-loaded nano- and microspheres with regular spherical shapes with narrow size distributions were obtained. The in vitro drug release behaviors of these drug release systems were investigated. The higher molecular weight of the polymer matrix resulted in a slower drug release rate. The drug release study showed the release of the drug could be effectively sustained by entrapment in the nano- and microspheres.