Free electron laser induces specific immobilization of heparin on polysulfone films

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.