Nitric oxide therapies

1. An apparatus comprising:

a cartridge including an inlet configured to receive a nitrogen dioxide-containing gas;

a porous polymer resin-based solid matrix comprising a surface-active material embedded within the porous polymer resin-based solid matrix, wherein the surface-active material comprises a silica gel present in an amount of 20% to 60%; and

an aqueous antioxidant wetting the surface-active material,

the cartridge is configured such that when the nitrogen dioxide-containing gas flows from the inlet and across the porous solid matrix, the aqueous antioxidant converts nitrogen dioxide to nitric oxide,

the cartridge includes an outlet configured to expel a nitric oxide-containing gas that has passed through the substrate.

2. The apparatus of claim 1 , wherein the aqueous antioxidant includes at least one of vitamin C or vitamin E.

3. The apparatus of claim 1 , wherein the aqueous antioxidant is a saturated solution of ascorbic acid.

4. The apparatus of claim 1 , wherein the aqueous antioxidant includes at least one of ascorbic acid, alpha tocopherol, or gamma tocopherol.

5. The apparatus of claim 1 , further comprising a source of nitrogen dioxide fluidically coupled to the inlet of the cartridge.

6. The apparatus of claim 1 , further comprising a permeation cell containing at least one of dinitrogen tetroxide or nitrogen dioxide fluidically coupled to the inlet of the cartridge.

7. The apparatus of claim 1 , wherein the cartridge is configured such that the aqueous antioxidant converts the nitrogen dioxide to nitric oxide at ambient temperature.

8. The apparatus of claim 1 , wherein the porous polymer resin-based solid matrix includes 35 to 70 mesh silica gel.

9. The apparatus of claim 1 , further comprising a pump configured to pass the nitrogen dioxide-containing gas over the porous polymer resin-based solid matrix.

10. The apparatus of claim 1 , wherein the nitrogen dioxide-containing gas can be caused to flow across the porous polymer resin-based solid matrix by human inhalation.

11. The apparatus of claim 1 , wherein the aqueous antioxidant is nontoxic.

12. The apparatus of claim 1 , wherein the cartridge is configured to remove all nitrogen dioxide from the nitrogen dioxide-containing gas.

13. A method comprising:

conveying a nitrogen dioxide-containing gas to a cartridge; wherein the cartridge comprises a porous polymer resin-based solid matrix comprising a surface-active material embedded within the porous polymer resin-based solid matrix, wherein the surface-active material comprises a silica gel present in an amount of 20% to 60%, and wherein the porous polymer resin-based solid matrix is wetted with an aqueous antioxidant;

passing the nitrogen dioxide-containing gas through the cartridge to convert the nitrogen dioxide to a nitric oxide and to produce a nitric oxide-containing gas; and

delivering the nitric oxide-containing gas to a patient.

14. The method of claim 13 , wherein the aqueous antioxidant is at least one of vitamin C or vitamin E.

15. The method of claim 13 , wherein the nitrogen dioxide-containing gas is conveyed from a permeation tube containing liquid dinitrogen tetroxide.

16. The method of claim 13 , wherein the nitrogen dioxide-containing gas is conveyed to the cartridge by a fan.

17. The method of claim 13 , wherein the nitrogen dioxide-containing gas is conveyed to the cartridge by the patient's inhalation.

18. A method comprising:

sintering a polymeric resin and silica gel, thereby forming a porous polymer resin-based solid matrix where the silica gel is embedded in the porous polymer resin-based solid matrix and is present in an amount of 20% to 60%;

wetting the porous polymer resin-based solid matrix with an antioxidant; and

placing the porous polymer resin-based solid matrix in a cartridge such that the cartridge is configured to convert nitrogen dioxide to nitric oxide.

19. The method of claim 18 , wherein the antioxidant is vitamin C.