Surface modification of high density polyethylene tubes by coating chitosan, chitosan hydrogel and heparin

Chitosan and chitosan hydrogel were immobilized on both the inside and outs ide surfaces of high density polyethylene (HDPE) tubes with 2.5x4 mm diamet ers. First, acrylic acid was grafted on the surfaces of HDPE by electron be am (2.5 Mrad) preirradiation method. Then chitosan/HCl and chitosan/lactic acid solutions were coated on the modified hydrophilic HDPE surfaces, the l atter could form a pH-sensitive hydrogel layer on the surfaces. The tube su rfaces were further modified with heparin by surface interpenetrating metho d to improve blood compatibility. ATR-FTIR and ESCA methods were used to ch aracterize the coated surfaces. The morphology changes were monitored by Sc anning Electron Microscope (SEM).