Introduction of surface functional groups onto biomaterials by glow discharges.

An attempt was made to graft the monomer HEMA to the polymer surface by "Glow discharge" technique. Experiments were carried out for different surfaces varying the exposure times of samples to HEMA and also as a function of glow discharge time. It was found that as the percentage of grafting increases the hydrophilicity also increases. Contact angle measurements were performed on these substrates, which confirmed the hydrophilic nature of the grafted samples compared to the controls. The role of protein adsorption and their effects to modulate the blood polymer interaction is briefly discussed. When a foreign material comes in contact with blood, the initial event is the adsorption of plasma proteins in parallel with the adhesion of platelets to the material. Albuminated surfaces discourage platelet adhesion while fibrinogen enhances the platelet attachment and thrombosis. Hence a decreased ratio of fibrinogen to albumin on a substrate can be correlated as an indication to its improved blood compatibility. Fibrinogen to albumin ratios of the grafted samples showed a reduction, indicating that albumin adsorption is high; which may make the modified surfaces non-thrombogenic.