A new method for analysis of the adsorbed plasma protein layer on biomaterial surfaces

The composition and dynamics of the protein film adsorbed onto surfaces from blood plasma remains unknown to biomaterials development. In situ radioiodination followed by elution and electrophoretic analysis has been demonstrated as a sensitive and versatile technique for analysis of these films. Iodine-125I was incorporated into protein using iodine monochloride. After film washing, and elution with sodium dodecylsulfate (SDS), proteins were subject to SDS gel electrophoresis for MW determination. Disulfide bond reduction with dithiothreitol was also employed to detect the presence of protein subunits. Fibrinogen, albumin and IgG were readily identified when adsorbed from a single protein solution onto teflon or silicone rubber. Electrophoretic analysis of the protein layer adsorbed from plasma revealed a complex pattern of up to 8 iodinated protein species. Iodinated protein with electrophoretic behavior consistent with fibrinogen and albumin was always found after plasma exposure, but proteins of apparent MW 7-10,000; 12,000; 25,000 and others remain unidentified. Adsorbed protein patterns varied with plasma source, type of material, and time of plasma exposure.