Electrospun fibers of acid-labile biodegradable polymers containing ortho ester groups for controlled release of paracetamol.

The local delivery and controllable release profiles make electrospun ultrafine fibers as potential implantable drug carriers and functional coatings of medical devices. There are few attempts to form acid-labile electrospun fibers, whose release behaviors respond to the local environment and fiber characteristics. In the current study a novel strategy was presented to synthesize biodegradable pH-sensitive polymers containing ortho ester groups. The acid-labile segments were synthesized through reacting 3,9-dimethylene-2,4,8,10-tetraoxaspiro [5.5] undecane with 1,10-decanediol or poly(ethylene glycol), which were further copolymerized with D,L-lactide to obtain triblock copolymers. Biodegradable acid-labile polymers were electrospun with the encapsulation of paracetamol as a model drug. In vitro release study showed that the total amount of drug released from acid-labile polymeric fibers was accelerated after incubation into acid buffer solutions, and the amount of initial burst release and sustained release rate were significantly higher for matrix polymers with hydrophilic acid-labile segments. In vitro degradation study indicated that the electrospun fibers containing acid-labile segments were stable in neutral buffer solution, but the molecular weight reduction of matrix polymers, the morphological changes and mass loss of fibrous mats were significantly enhanced under acid circumstances.