Silastic albumin adsorption

Figure 5. Albumin adsorption isotherms on Silastic before and after fat removal from the albumin. Films were equilibrated at 37°C for 20 hrs at the depicted albumin concentration in O.OIM HEPES, 0.147M NaCl, 0.02% azide, pH 7.4 and then rinsed with buffer at room temperature by the dilution displacement technique. Fraction V albumin (NBC 2106) was used untreated or defatted with charcoal (see Table III...

Figure 8. Fibrinogen-albumin competition adsorption onto Silastic, poly(NVP)/ Silastic, and poly(H EM A)/Silastic. Untreated Silastic and films grafted with poly(NVP) (2.7 mg/cm ) or poly(HEMA) (5.8 mg/cm/) were equilibrated in solutions containing 0.01 mg fibrinogen/ml plus the concentration of albumin corresponding to the albumin/fibrinogen ratio depicted. The solvent was O.OIM HEPES, 0.147M NaCl, 0.02% azide, pH 7.4. Equilibration was carried out at 37°C for 20 hrs and was ended by dilution displacement rinse with buffer. The films were further rinsed by soaking for at least 20 hrs prior to counting to determine the fibrinogen on the film.

The reduced adsorption of fibrinogen from plasma onto Silastic and poly (HEMA)/Silastic compared with that from pure buffered saline solutions could be caused by competition from other proteins for the adsorption sites. Albumin and y-globulin are both present in plasma in relatively high concentrations (about 45 and 10 mg/ml, respectively, compared with ca. 3 mg/ml for fibrinogen), so either might compete effectively with fibrinogen for adsorption. To test this, mixtures of I-fibrinogen... 

Figure 20 summarizes the result of BSA adsorption to the polymer films. We used BSA as model for protein because albumin is the protein that is most prominently present in human blood serum. The BSA adsorption onto regenerated cellulose, which had a highly hydrophilic surface, was extremely low. These data gave the same result reported in the previous study [70]. On the other hand, the adsorbed amounts of BSA onto aramid and nylon were high (0.5-0.6 p,g/cm ). For the PASs, the amount of BSA was almost half the amounts of those with aramid and nylon, but similar to that for SILASTIC 500-1, and more than that of the regenerated cellulose. There was no difference in the adsorbed amounts onto the three samples of PASs. In the previous work, PDMS blocks were condensed at the outermost surface of PAS [10]. The phenomenon of protein adsorption onto PAS seems to be due to the low surface free-energy of the PAS surface [71-73] caused by the condensation of PDMS blocks on the outermost surface of PAS. Therefore, the BSA was bound onto PAS surface as well as the surface of the silicone rubber [74,75]. 

---