Specific Immobilization of Heparin on Polysulfone Films by Free Electron Laser and Ion Irradiation

A novel way for specific immobilization of heparin on polysulfone (PSF) via laser irradiation is summarized. Free Electron Laser (FEL) wavelengths tuned to 6.18 and 6.31 µm, the typical absorption band of carboxyl group of heparin and stretching absorption of aromatic rings in polysulfone respectively, were chosen to illuminate thin heparin film formed on PSF surfaces. The modification at the wavelength of 6.18 µm resulted in surface hydrophilicity and resistance to platelet adhesion. Surface elemental analysis on XPS implied the bounding of heparin on polymer surface. On the contrary, the modification at the wavelength of 6.31 µm showed no statistical difference with controls in terms of hydrophilicity as well as elemental composition. This effect of variation in laser wavelengths is considered as coming from the structural and environmental differences of light-absorbing groups.