Nitric oxide delivery devices
A gas delivery device includes a nitric oxide generating system. The system has a medium including i) a source of nitrite ions, or ii) a source of nitrite ions and a Cu(II)-ligand complex. A working electrode is in contact with the medium, wherein i) when the medium includes the source of nitrite ions, the working electrode is a copper containing conductive material or a base material coated with a copper containing conductive material, or ii) when the medium includes the source of nitrite ions and the Cu(II)-ligand complex, the working electrode is platinum, gold, carbon, a carbon coated material, and/or mercury. A reference/counter electrode is in contact with the medium and electrically isolated from the working electrode. An inlet conduit is to deliver oxygen gas to the medium, and an outlet conduit is to transport a stream of oxygen gas and nitric oxide from the medium.
1. A method for generating nitric oxide, comprising:
providing a medium including a Cu(II)-ligand complex and an excess of a source of nitrite ions; and
applying a cathodic voltage to a working electrode positioned in contact with the medium, thereby reducing the Cu(II)-ligand complex to a Cu(I)-ligand complex which reacts with some nitrite from the source of nitrite ions to form the nitric oxide, wherein the nitric oxide is not bound to the Cu(I)-ligand complex and wherein excess nitrite is bound to the Cu(I)-ligand complex.
2. The method as defined in claim 1 , further comprising modulating a flux of the generated nitric oxide by any of altering an amount of a surface area of the working electrode that is exposed to the medium, or altering a concentration of any of the Cu(II)-ligand complex or the source of nitrite ions in the medium, or altering a magnitude of the cathodic voltage over time.
3. The method as defined in claim 1 wherein the applying of the cathodic voltage is accomplished at predetermined intervals.
4. The method as defined in claim 1 wherein the applying of the cathodic voltage includes:
applying a first cathodic voltage to increase NO production for a predetermined time period; and then
applying a second cathodic voltage that is less negative than the first cathodic voltage to decrease NO production after the predetermined time period has expired.
5. The method as defined in claim 1 , further comprising transporting the nitric oxide out of the medium without performing additional steps to oxidize the ligand complex.
6. The method as defined in claim 1 , further comprising:
introducing an oxygen gas stream into the medium, whereby the oxygen gas stream picks up the nitric oxide; and
transporting the oxygen gas stream including the nitric oxide out of the medium.
7. The method as defined in claim 1 wherein the Cu(II)-ligand complex is selected from the group consisting of Cu(II)-tri(2-pyridylmethyl)amine, Cu(II)-tri(2-dimethylamino)ethyl]amine, Cu(II)-tri(2-pyridylmethyl)phosphine, and combinations thereof.
8. The method as defined in claim 1 wherein the medium includes at least 100 mM of the source of nitrite ions.