Reducing O2 sensitivity in electrochemical nitric oxide releasing catheters: An O2-tolerant copper(II)-ligand nitrite reduction catalyst and a glucose oxidase catheter coating

Abstract

Electrocatalytic nitric oxide (NO) generation from nitrite (NO2–) within a single lumen of a dual-lumen catheter using CuII-ligand (CuII-L) mediators have been successful at demonstrating NO’s potent antimicrobial and antithrombotic properties to reduce bacterial counts and mitigate clotting under low oxygen conditions (e.g., venous blood). Under more aerobic conditions, the O2 sensitivity of the Cu(II)-ligand catalysts and the reaction of O2 (highly soluble in the catheter material) with the NO diffusing through the outer walls of the catheters results in a large decreases in NO fluxes from the surfaces of the catheters, reducing the utility of this approach. Herein, we describe a new more O2-tolerant CuII-L catalyst, [Cu(BEPA-EtSO3)(OTf)], as well as a potentially useful immobilized glucose oxidase enzyme-coating approach that greatly reduces the NO reactivity with oxygen as the NO partitions and diffuses through the catheter material. Results from this work demonstrate that very effective NO fluxes (>1*10−10 mol min−1 cm−2) from a single-lumen silicone rubber catheter can be achieved in the presence of up to 10% O2 saturated solutions.