Covalent immobilization of heparin has been developed to reduce the amount
of heparin administered systematically during long-term dialysis. Recently,
it was doubted partially because of the complexion during immobilization p
rocess. In this study, we investigated a novel method for specific immobili
zation of heparin on polysulfone (PSF) via free electron laser (FEL) irradi
ation. Laser wavelengths of 6.18 or 6.31 mum, the typical absorption bands
of carboxyl groups of heparin and aromatic rings in PSF. respectively, were
chosen to irradiate the thin heparin membrane formed on PSF surfaces. The
amount of heparin immobilized on PSF was measured by the toluidine blue met
hod. The binding of heparin on PSF was analyzed by X-ray photoelectron spec
troscopy (XPS). The immobilization of heparin resulted in a hydrophilic sur
face on which decreased platelet adhesion was observed. The efficiency diff
erences, depending on laser wavelengths, were discussed from the point of v
iew of structural and environmental differences of light-absorbing groups.