Biomembranes as models for polymer surfaces. V. Thrombelastographic studies of polymeric lipids and polyesters.

Our approach to the design of haemocompatible biomaterials is based upon the concept that coating a polymer or metal surface with phosphatidylcholine polar groups (corresponding to the major phospholipid of the human erythrocyte outer cell membrane) will improve their haemocompatibility. We have examined the effect on blood coagulation of a number of substrates: those normally used in prosthetic devices such as polyethylene terephthalate (Dacron), expanded polytetrafluoroethylene, silicone and new polymers which contain the phosphatidylcholine head group (phosphorylcholine). The effect on coagulation of blood exposed to these substrates was determined by the technique of material thrombelastography, a relatively new method for the in vitro screening of biomaterial thrombogenicity. The results obtained with Dacron, polytetrafluoroethylene and silicone are compared with those obtained with a phospholipid-dipalmitoyl-phosphatidylcholine, a polymerized phospholipid-diacetylenicphosphatidylcholine, and a range of recently synthesized polyesters, each of which contains the phosphorylcholine polar head group.