Development and characterization of heparin-immobilized polycaprolactone nanofibrous scaffolds for tissue engineering using gamma-irradiation

Abstract

Polycaprolactone (PCL) has been considered a useful material for orthopedic devices and osseous implants because of its biocompatibility and bone-forming activity. However, PCL-based scaffolds have hydrophobic surfaces that reduce initial cell viability. In this study, we fabricated surface-modified PCL nanofibers for tissue engineering using radiation technology. We supplemented the hydrophilicity of the PCL nanofibers by introducing 2-aminoethyl methacrylate (AEMA) through gamma-irradiation and subsequently immobilized heparin onto the nanofibers using the EDC/NHS reaction. The SEM images show that there is almost no change in the morphology of nanofibers after radiation grafting of AEMA and heparin-immobilization onto PCL nanofibers. The surface properties of the scaffolds were characterized by ATR-FTIR, XPS, and fluorescamine staining in order to confirm the successful grafting of AEMA onto the PCL nanofibers. Immobilization of heparin was also confirmed by the amide I (1650 cm⁻¹) and amide II group (1550 cm⁻¹) from ATR-FTIR. The amounts of heparin were drastically increased on the AEMA–PCL nanofibers as revealed by TBO assay. The initial cell viability of hMSCs was significantly increased on the AEMA grafted nanofibers but grew slowly on heparin-immobilized nanofibers. The cumulative release of bone morphogenetic protein-2 (BMP-2) was slow and continuous onto the heparin-immobilized nanofibers (18.13 ± 3.87 μg mL⁻¹) compared to PCL nanofibers (20.25 ± 1.45 μg mL⁻¹). Therefore, heparin-immobilized nanofibers may be a good tool for tissue engineering applications using radiation technology.