Paclitaxel-loaded composite fibers: microstructure and emulsion stability

New core/shell fiber structures loaded with paclitaxel were developed and studied. These composite fibers are ideal for forming thin, delicate, biomedically important structures for various applications. Possible applications include fiber-based endovascular stents that mechanically support blood vessels while delivering drugs for preventing restenosis directly to the blood vessel wall, or drug delivery systems for cancer treatment. The core/shell fiber structures were formed by "coating" nylon fibers with porous paclitaxel-containing poly(DL-lactic-co-glycolic acid) structures. Shell preparation ("coating") was performed by freeze-drying water in oil emulsions. The present study focused on the effects of the emulsion's formulation (composition) and processing conditions on the porous shell structure, which actually reflects the emulsion's stability and also the drug release profile from the fibers. In general, extremely porous "shell" structures were obtained with good adhesion to the core fiber. An increase in the emulsion's drug content and copolymer composition demonstrated a significant effect on pore size and distribution, because of enhanced emulsion instability, whereas the homogenization rate and duration had only a slight effect on the pores' microstructure. The thermodynamic parameters in the studied system are thus more important than the kinetic parameters in determining the emulsion's stability and the shell's porous structure.