Characterization of PCL vascular grafts The micromorphology of the PCL vascular grafts was examined by scanning electron microscopy (SEM,HitachiS-3400N). The average fiber diameter and pore size were analyzed using ImageJ software. The (PEI/HEP) 10 and (PEI/EGCG/HEP) 10 were prepared on the surfaces of quartz substrates to determine the existence of EGCG with UV/V is spectrophotometer (PerkinElmer LAMBDA 850,USA) in the range of 200–600nm. XPS measurement was performed with a XSAM 800X-ray photoelectron microscopy (Kratos,UK),the deconvoluted spectra were fitted with XPSPEAK 41 software. Mechanical properties of PCL vascular grafts were tested on an Instron 4310 Testing Machine (Instron,USA). Grafts (length, 4cm;gauge length,2cm) were pulled longitudinally at a strain rate of 10mm/min until rupture. Each test was repeated three times.