adhesion and activation of platelets and polymorphonuclear granulocyte cells at tio2 surfaces the initial reactions of two tio2 surfaces with blood were investigated by shorttime exposure to capillary blood and analysis of surfaceadsorbed plasma proteins and surfaceadhering cells by using immunofluorescence techniques antibodies directed against platelet membrane antigen and pselectin were used to visualize platelet adhesion and activation acridine orange and anticd11b were used to detect adhesion and activation of polymorphonuclear granulocytes pmns antibodies against thrombospondin were used as markers for platelet alphagranules the fluorescence intensity was quantitated by computeraided image analysis commercially pure polished sheet titanium was oxidized in two different ways 1 the natural oxide was dissolved with hydrofluoric acid and a new oxide layer was grown by oxidation in nitric acid or 2 annealing was performed at 700 degrees c in air auger electron spectroscopy and xray photoelectron spectroscopy showed that both surfaces had similar composition consisting of tio2 covered by a carbonaceous surface contamination layer the thickness of the oxide layer was 4 nm on the acidoxidized surface and 39 nm on the annealed surface optical profilometry and scanning electron microscopy showed that the acidoxidized surface was rough and the annealed surface was smooth the fibrinogenprothrombinthrombin ratio in the initial protein film differed between the surfaces the number of adhering platelets was larger at the surface with a high surface concentration of adsorbed fibrinogen platelet activation cd62 and priming of pmns cd 11b were also significantly higher on the acidoxidized surface the results indicate that nonself recognition of biomaterials is an array of transient reactions comprising proteinmaterial proteincell and cellcell interactions