Applications of Tracers in the Study of Biocompatible Surfaces.

The incorporation of phosphoryl choline onto synthetic surfaces has been found to greatly increase the biocompatibility of these materials. Recent developments have led to the use of phosphoryl choline containing polymers as biocompatible coatings. In order to determine the surface stability of these polymers, tritiated versions were prepared by the reduction of unsaturated precursor polymers with tritium gas. The regiospecificity of the labelling was confirmed by the use of tritium NMR spectroscopy including lanthanide shift reagent studies. A radio-gel permeation chromatography method was developed to determine the radiochemical purities of the tritiated polymers. From this analysis the radiochemical purities were shown to be greater than 98%. A selection of the tritiated polymers were coated onto various medical materials and incubated over a ten day period with buffers ranging from pH 4-9 at temperatures of 20°C, 40°C and 60°C. No significant leaching from these surfaces was observed. Phosphoryl choline containing compounds are thought to confer biocompatible properties because of the ability of the headgroup to associate large quantities of water. The final chapter describes an investigation of the ability of phosphoryl choline and other structurally similar headgroups to associate with deuteriated water by studying the T1 relaxation times of the water molecules using deuterium NMR spectroscopy. A comparison of these results and those obtained from haemocompatibility tests indicated that no simple relationship was apparent between the ability to bind water and provide a biocompatible surface