(429a) Incorporation and Release of Hydrophobic and Hydrophilic Bioactive Agents Using Novel Microfiber Scaffolds Produced through Electrostatic Processing

Polymers have been employed as materials for drug delivery applications due to several advantages that they hold over more traditional delivery systems, including low toxicity, controlled degradation, ease of manufacturing, tailored release profiles and targeted or stimuli sensitive delivery. However, although polymers have radically improved the range and diversity of drug delivery technology there is considerable room for further development. Electrostatic processing, including electrospinning and electrospraying, has been investigated as a means of polymer processing to form non-woven mats of small-diameter fibers or particles for use in delivery of bioactive agents, as it allows for control of the properties of the fibrous mats, which may provide for the development of specific degradation and release profiles. Described herein is the development of and release of agents from inventive fibrous structures created by novel electrostatic processing techniques, which were used to emit both hydrophilic and hydrophobic molecules. The novel structures used as delivery agents were mats of either fibers surface decorated with polymer spheres or fibers with aqueous pockets entrained within the polymer fiber shell. These structures are fabricated by two different extensions of standard electrospinning processes. Delivery systems for the incorporation and release of hydrophobic molecules consisted of mats of fibers of a non-biodegradable polymer decorated spheres of a degradable polymer into which the hydrophobic agent was incorporated. These structures were obtained by simultaneously electrostatically processing two solutions charged with opposite polarities, the first being the non-degradable polymer in a compatible solvent and the second being a solution of the degradable polymer and the hydrophobic drug in a suitable solvent. This results in two jets of polymer solution with opposite charges that interact midair, leading to the formation of fibers decorated with polymer spheres laced with the hydrophobic agent. Release of the hydrophobic molecules was achieved by degradation of the polymer particles, while maintaining fiber integrity, and release profiles were obtained. Delivery systems for the incorporation and release of hydrophilic molecules consisted of mats of fibers of a biodegradable polymer within which were entrained aqueous pockets containing the hydrophilic molecules. These structures were obtained by electrospinning a polymer solution containing a suspension of the hydrophilic drug in water. Degradation of the polymeric fibers resulted in release of the hydrophilic compounds, and release profiles of the hydrophobic molecules were obtained.