Fibrinogen adsorption films

Fibrinogen Adsorption from Plasma. Films were submerged in 2 ml of O.OIM HEPES, 0.I47M NaCl, 0.02% azide, pH 7.4. Eight ml of citrated plasma (pH 7.6) containing I-fibrinogen was added, and the solutions were mixed by swirling the films. 

The poly (HEM A) sheets were prepared by B. Ratner using a special technique he developed. The HEMA solutions were poured between glass plates, and polymerization was chemically initiated. The chemical and physical properties of this material are very similar to those of radiation-grafted poly (HEMA) insofar as protein adsorption is concerned. Heterogeneous or homogeneous poly (HEMA) films were made by polymerization in solvents in which the poly (HEMA) is insoluble or soluble, respectively the result is a white opaque material in the first case and a transparent material in the second case. The resulting films were washed free of excess monomer and then soaked in the buffer to be used in the fibrinogen adsorption experiment for 10 days at 37 °C prior to the actual experiment. 

Figure 4. Fibrinogen adsorption onto radiation-grafted poly(HEMA)/ Silastic Effect of graft level. Films grafted to the degree depicted were equilibrated at 37°C for 20 hrs in 1 mg/ml fibrinogen solution in 0.01 M HEPES, 0.147M NaCl, 0.02% azide, pH 7.4 and then rinsed by dilution displacement and extensive soaking with buffer at room...

Figure 7. Plasma fibrinogen adsorption onto poly( HEM A)/Silastic. Poly-(HEMA)-grafted Silastic (ca. 5 mg/cm ) films were equilibrated in a plasma solution (containing H-fibrinogen) at 37°C for the time depicted and then rinsed briefly by the dilution displacement technique with 0.01 M HEPES, 0.147M NaCl, pH 7.4, and then counted.

Fibrinogen adsorption onto the most highly grafted poly(HEMA)/Silastic films (5.8 mg/cm ) was the same as onto films having only about one-fifth the graft, but films with grafts much below this point (1 mg/cm ) showed increased adsorption characteristic of the underlying Silastic. 

CP composites of both poly(vinyl alcohol) (PVA) [83-88] and poly(ethylene glycol) (PEG) [87,89,90] have been fabricated by both chemical and electrochemical polymerization of either monomer solution loaded or dispersed into hydrogel networks. Li et al. reported that tetraethylammonium perchlorate (TEAP) doped PPy-PVA composite was more hydrophilic than PPy/TEAP film and showed less fibrinogen adsorption on the surface than the CP control film. The PPY-PVA composite maintained intrinsic conductivity of PPy/TEAP film (7 S cm ) and the porous structure of the composite promoted neural cell attachment and spreading in the model clonal line, PC 12 [86]. 

Fig. 4 Fibrinogen adsorption and desorption curves for ah uncoated polyurethane film (1) and for carbon layers...

Based on the relationship between protein adsorption and thromboge-nicity, a method was reported for fibrinogen adsorption/desorption measurements as a prescreening method. Processes for the coating of polymers with poly-acrybnitrile and with carbon were discussed, and results on layers on flat films, the inside of tubes and vascular prostheses, and on membranes were described. 

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.

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