BLOOD COMPATIBILITY OF POLYPROPYLENE SURFACES IN RELATION TO THE CRYSTALLINE-AMORPHOUS MICROSTRUCTURE

Blood-contacting properties of polypropylene surfaces with different c rystalline states at the surface layer were examined in terms of plasm a protein adsorption and changes in cytoplasmic free Ca2+ levels in pl atelets. Though the wettability of polypropylene surfaces was almost c onstantly independent from the surface layer crystallinity and interla mellar spacing, an increase in adhesiveness was observed with decreasi ng surface layer crystallinity and interlamellar spacing. It is sugges ted that the surface properties of the sheets varied in relation to th e crystalline-amorphous microstructure. Minimum magnitudes in albumin and fibrinogen adsorption were observed on the polypropylene surface w ith a particular surface layer crystallinity (c. 55 wt%). A decrease i n interlamellar spacing resulted in enhancing albumin adsorption and d iminishing fibrinogen adsorption. Transient phenomena in plasma protei n adsorption were observed on their surfaces with a plasma concentrati on. It is considered that the polypropylene surface with a particular crystalline-amorphous microstructure reduces the denaturation of adsor bed proteins. An increase in cytoplasmic free Ca2+ levels in platelets was prevented at the polypropylene surface with a surface layer cryst allinity of 55 wt%: the particular crystalline-amorphous microstructur e of such apolar surfaces as polypropylenes acts to reduce platelet ac tivation. Thus, it is concluded that the blood compatibility of polypr opylene surfaces is greatly improved by controlling a crystalline-amor phous microstructure at the surface layer.