Novel composite fiber structures to provide drug/protein delivery for medical implants and tissue regeneration.

A novel class of bioresorbable composite (core/shell) fiber structures loaded with bioactive agents was developed and studied. These unique polymeric structures are designed to combine good mechanical properties with a desired controlled release profile, in order to serve as scaffolds for tissue regeneration applications and as basic elements of medical implants. These core/shell fiber structures were formed by "coating" core polymer fibers with drug/protein-containing poly(dl-lactic-co-glycolic acid) porous structures. The shell preparation ("coating") was performed by the freeze-drying of water-in-oil emulsions. Both water soluble and water insoluble agents can be incorporated in these structures and their activity is preserved, since the fiber fabrication requires neither high temperatures nor harsh solvents in the vicinity of the bioactive agents. Examples for release profiles of protein (horseradish peroxidase) and drug (paclitaxel) are presented. We have demonstrated that appropriate selection of the emulsion's parameters can yield a variety of new core/shell fiber structures with desirable drug/protein release behavior. This will lead to the engineering of new implants and scaffolds, and will advance the field of tissue regeneration and medical implants.