Development of PCL/Ibuprofen Tubes for Peripheral Nerve Regeneration

Polymeric bioabsorbable tubes can be used as drug delivery systems and guides for cellular growth in peripheral nerve regeneration. In this study polycaprolactone/ibuprofen tubes manufactured by melt extrusion technique were investigated under different screw speeds and processing temperatures. To assess the structure and properties of PCL/ibuprofen tubes, analysis was performed using scanning electron microscopy, X-ray diffraction, infrared spectroscopy, flexural tests and dynamic mechanical analysis (DMA). The drug delivery profile was obtained by determining the in vitro release of ibuprofen. Tubes of PCL/ibuprofen were prepared by vertical extrusion. The average values for the diameter and wall thickness of the PCL/ibuprofen tubes were 1.5mm and 250μm, respectively. The crystallinity values for the PCL/ibuprofen tubes were lower than those for the pure PCL tubes, probably due to the interaction of the drug with the polymer chains. The value for the flexural modulus of the PCL/ibuprofen tubes increased with the processing temperature and screw speed, which is probably due to better drug dispersion at higher temperature and higher shear rates. The preparation of the tubes using faster screw speeds led to higher values being obtained for the storage modulus in the DMA, indicating that the shear rate also affects the mechanical properties. The PCL/ibuprofen tubes had lower glass transition temperatures compared with pure PCL tubes, also suggesting interaction between ibuprofen and the PCL matrix. The results suggest that the PCL/ibuprofen tubes prepared by vertical extrusion using a screw speed of 17rpm and processing temperature of 140 ̊C were the most suitable for peripheral nerve regeneration offering appropriate dimensions and mechanical properties and an acceptable drug release profile.