Sulfonated poly(vinylidene fluoride) as a biomaterial: immobilization of urokinase and biocompatibility

The adsorption of urokinase (UK) on sulfonated poly(vinylidene fluoride) (PVDF) films was examined. The amount of adsorbed UK on sulfonated PVDF films increased linearly with the degree of the ion exchange capacity (IEC) of sulfonated film. Moderately sulfonated PVDF film (IEC = 0.25 meq/g) adsorbed 3 IU/cm2 UK, and highly sulfonated film (IEC = 0.54 meq/g) adsorbed 5 IU/cm2 UK. All UK-immobilized PVDF films were active for ten weeks. The presence of the sulfonated films in the culture of rat lymphocytes did not result in any change of their viability. The implant of the film (IEC greater than 0.48 meq/g) into the subcutaneous layer of rats resulted in the cell infiltration composed of lymphocytes and plasma cells or the blastogenesis within the surrounding tissues of the implant and the regional lymph nodes. On the contrary, the implant of the films (IEC less than 0.27 meq/g) did not exert any visible changes, indicating that the lightly sulfonated films may be applicable in the sense of biocompatibility in vivo.