Multi-layer nanofibrous tubes with dual drug-release profiles for vascular graft engineering

Abstract

Currently available synthetic grafts demonstrate moderate success at the macrovascular level, but there is still a problem with thrombus formation at the microvascular scale (<6 mm inner diameter). The aim of this study was to fabricate multi-layer drug-loaded polycaprolactone (PCL)/oligomeric proanthocyanidin (OPC) nanofiber tubes with two types of release kinetics to protect against both short- and long-term thrombosis. Multi-layer PCL nanofiber tubes with layer numbers of 2, 3, 5, and 10 were prepared and then their mechanical and OPC release properties were studied. The morphology of the multi-layer tubes was characterized by scanning electron microscopy and digital microscopy. Fourier transform infrared spectroscopy revealed that the PCL nanofibers exhibited characteristic peaks. X-ray diffraction measurements showed the crystallinity of PCL. Differential scanning calorimetry revealed the melting temperature of PCL. Finally, the release profiles of the layers with two distinct types of release kinetics were measured. The results indicated that the drug release from the interlayer and electrospun membrane showed separate and distinct profiles. Most of the OPC was released rapidly during the 1.5 h of the trial. In contrast, the release from the nanofibers was sustained for 62 days.