In Vivo Biocompatibility and Analytical Performance of Intravascular Amperometric Oxygen Sensors Prepared with Improved Nitric Oxide-Releasing Silicone Rubber Coating

Abstract

The in vivo biocompatibility and analytical performance of amperometric oxygen-sensing catheters prepared with a new type of nitric oxide (NO)-releasing silicone rubber polymer (DACA/N₂O₂ SR) is reported. The NO-release silicone rubber coating contains diazeniumdiolated secondary amine sites covalently anchored to a dimethylsiloxane matrix. Narrow diameter (0.9 mm, o.d.) silicone rubber tubing coated with this polymer can be employed to construct functional oxygen-sensing catheters that release NO continuously at levels >1 × 10^-10 mol/cm²-min for more than 20 h. In vivo evaluation of such sensors within the carotid and femoral arteries of swine over a 16-h time period demonstrates that sensors prepared with the new NO-release coating exhibit no significant platelet adhesion or thrombus formation, but control sensors (non-NO release) implanted within the same animals do show a high propensity for cell adhesion and bulk clot formation. Furthermore, the in vivo analytical data provided by sensors fabricated with NO-release coatings (N = 9) are shown to be statistically equivalent to PO₂ levels measured in vitro on discrete samples of blood. Control sensors (N = 9) placed within the same animals yield average PO₂ values that are statistically different (p < = 0.05) (lower) from both the levels measured on discrete samples and those provided by the NO-release sensors over a 16-h in vivo monitoring period.