Plasma protein adsorption pattern on characterised ceramic biomaterials

The protein/biomaterial interactions of three biomaterials used in hard tissue surgery were studied in vitro. A dynamic flow system and two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) were used to investigate the adsorption of proteins from diluted human plasma on hydroxyapatite, alumina and zirconia, with regard to total proytein binding capacity, relative binding capacity for specific proteins and flow-through and desorption patterns. The ceramics were characterised regarding physico-chemical properties; namely, chemical composition by elementary analyses and specific surface, pore volume and pore size distribution using BET-method and Hg-porosimetry. The materials were found to adsorb a surprisingly low amount of plasma proteins, leaving more than 70% of the surface free. The cellular response will therefore be highly affected by the physico-chimical properties of the materials, in contrast to a surface fully covered with proteins. Regarding the adsorption of proteins, most of them exhibited similar flow-through patterns on the three adsorbents. The exceptions with different flow-through patterns were apolipoprotein D (Apo D), apolipoprotein J (Apo J), complement factor C1s (C1s), complement factor C3 (C3), ceruloplasmin, fibrinogen, alpha-1 B glycoprotein and alpha-2 HS glycoprotein and serum retinal-binding protein (SRBP). The role of these proteins on acceptance or rejection of implants has to be investigated.