Methods for determining oxygen concentration with protoporphyrin IX

1. A method for determining a concentration of oxygen in a compartment, the method comprising:

exciting protoporphyrin IX in the compartment, wherein protoporphyrin IX, when excited, exhibits a luminescence and/or transient absorption having a lifetime and wherein the lifetime of the luminescence and/or transient absorption is dependent on the oxygen concentration in the compartment,

measuring the lifetime of the luminescence and/or transient absorption exhibited by protoporphyrin IX in the compartment, and

correlating the lifetime of the luminescence and/or transient absorption with the concentration of oxygen in the compartment.

2. The method according to claim 1 , wherein the luminescence and/or transient absorption comprises delayed fluorescence and/or triplet-triplet absorption.

3. The method according to claim 1 , wherein the protoporphyrin IX in the compartment is photo-excited.

4. The method according to claim 1 , wherein the compartment comprises a cell.

5. The method according to claim 1 , wherein the compartment comprises an organelle.

6. The method according to claim 5 , wherein the organelle comprises a mitochondrion.

7. The method according to claim 1 , wherein the compartment comprises at least part of a tissue.

8. The method according to claim 1 , wherein the compartment comprises an organ.

9. The method according to claim 1 , wherein the compartment comprises a tumor.

10. The method according to claim 1 , wherein the compartment comprises microcirculation.

11. The method according to claim 1 , wherein the compartment is present in a culture medium.

12. The method according to claim 1 , wherein the compartment comprises a cell suspension.

13. The method according to claim 1 , wherein the lifetime of the luminescence and/or transient absorption is compared with a reference.

14. The method according to claim 1 , wherein the lifetime of the luminescence and/or transient absorption is measured in the time-domain.

15. The method according to claim 1 , wherein the lifetime of the luminescence and/or transient absorption is measured in the frequency-domain.

16. The method according to claim 1 , wherein multi-photon excitation is applied.

17. The method according to claim 1 , wherein two-photon excitation is applied.

18. The method according to claim 1 , wherein a precursor of protoporphyrin IX is administered to the compartment, which precursor is able to be converted into at least protoporphyrin IX, and wherein the protoporphyrin IX derived from the precursor is excited.

19. The method according to claim 18 , wherein the lifetime of the luminescence and/or transient absorption is measured within four hours of administering precursor of protoporphyrin IX to the compartment.

20. The method according to claim 18 , wherein the precursor is 5-aminolevulinic acid.

21. The method according to claim 1 , wherein the protoporphyrin IX is excited by a device comprising:

means for exciting protoporphyrin IX in the compartment, and

means for measuring the lifetime of the luminescence and/or transient absorption in the compartment,

and further wherein said device measures the lifetime of the luminescence and/or transient absorption in the compartment.

22. A method for determining the concentration of oxygen in a compartment, said compartment selected from the group consisting of a cell, an organelle, a mitochondrion, a tissue, an organ, a tumor, and microcirculation, the method comprising:

exciting, in the compartment, protoporphyrin IX, wherein protoporphyrin IX, when excited, exhibits luminescence and/or transient absorption having a lifetime, wherein the lifetime of the luminescence and/or transient absorption is dependent on the oxygen concentration in the compartment,

measuring the lifetime of the luminescence and/or transient absorption exhibited by protoporphyrin IX in the compartment,

comparing the measured lifetime of the luminescence and/or transient absorption exhibited by protoporphyrin IX in the compartment with a reference, and

correlating the measured lifetime of the luminescence and/or transient absorption exhibited by protoporphyrin IX compartment with the concentration of oxygen in the compartment.