Synthesis of biomaterials by swift heavy ion grafting: Preliminary results of haemocompatibility

Abstract

Sulfonate and sulfonamide groups were introduced on styrene which was radiation grafted on poly(vinylidene difluoride) (PVDF) to improve surface thrombogenicity. Irradiation was performed with swift heavy ions ( E > 1 MeV/amu) and the grafting of styrene was achieved by the peroxide method. A characterisation of surface topography was carried out by Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays (EDXA). Compared to the SEM micrograph of PVDF, the SEM micrographs of the polystyrene grafted PVDF (PVDF-g-PS) and the functionalised polystyrene grafted PVDF (PVDF-g-PSf) show circular “islands” of different sizes. EDXA analysis shows that the amount of fluorine is directly dependent on the presence of these islands. When the styrene is grafted, the amount of fluorine is lower. The swift heavy ions induce significant grafting only in small regions (the latent tracks) of the polymer. Fibrinogen and albumin adsorption from plasma on these materials was quantitatively assessed using 125I-labelled proteins prepared under a quality controlled procedure. The amount of adsorbed proteins is greater in the case of PVDF-g-PSf. For PVDF-g-PSf the rates of exchanged proteins increases when the functionalisation yield increases. The distribution of bound proteins, determined by microauto-radiography seems to be homogeneous on the three different materials studied here.