PHOTOERADICATION OF MICROORGANISMS WITH PULSED PURPLE OR BLUE LIGHT

• US 20180280723A1
• Filed: 04/18/2018
• Published: 10/04/2018
• Est. Priority Date: 05/26/2016
• Status: Active Grant

• Current Assignee: San Diego State University (SDSU) Research Foundation
• Original Assignee: CareWear Corp., San Diego State University (SDSU) Research Foundation
• Inventors: ENWEMEKA, CHUKUKA S., CASTEL, JOHN C.
• Granted Patent: US 10,639,498 B2
• Time in Patent Office: Days
• CPC Class Codes: A23L 3/26 by irradiation without heating
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61L 2/08 Radiation
• CPC Class Codes: A61L 2/084 Visible light
• CPC Class Codes: A61L 2/16 using chemical substances
• CPC Class Codes: A61L 2202/11 Apparatus for generating biocidal substances, e.g. vaporisers, UV lamps
• CPC Class Codes: A61N 2005/0628 including a radiation sensor
• CPC Class Codes: A61N 2005/0632 Constructional aspects of the apparatus
• CPC Class Codes: A61N 2005/0651 Diodes
• CPC Class Codes: A61N 2005/0653 Organic light emitting diodes
• CPC Class Codes: A61N 2005/0663 Coloured light
• CPC Class Codes: A61N 5/0616 Skin treatment other than tanning
• CPC Class Codes: A61N 5/0624 for eliminating microbes, germs, bacteria on or in the body

Abstract

The present invention is directed to a system and method for photoeradication of microorganisms from a target. A light source is configured to irradiate the target with purple or blue light in a pulsed mode of irradiation at an average irradiance that preferably ranges from 0.1 mW/cm² to 20 mW/cm². An electronic circuit is configured to control the light source in accordance with an irradiation schedule that includes a plurality of irradiation sessions. The light source is controlled to provide the purple or blue light at a radiant exposure that preferably ranges from 0.5 J/cm² to 60 J/cm² during each of the irradiation sessions. The irradiation sessions are provided at a plurality of time intervals so as to cause photoeradication of all or a portion of the microorganisms.

Claims

1. A method for photoeradication of microorganisms from a target, the method comprising:

irradiating the target with purple or blue light in a pulsed mode of irradiation, wherein the light comprises a sequence of light pulses in which (a) the light pulses have a peak irradiance and a pulse duration sufficient to optically excite a photoactive molecule capable of photoeradication of the microorganisms and (b) the light pulses are separated by an off time sufficient to allow the photoactive molecule to return to a ground state creating an oxidation reaction that produces free radicals which destroy a cellular structure of the microorganisms, wherein the light causes photoeradication of all or a portion of the microorganisms.

2. The method of claim 1, wherein the light has a wavelength that ranges from 380 nm to 500 nm.

3. The method of claim 1, wherein the peak irradiance of the light pulses ranges from 0.3 mW/cm² to 60 mW/cm², the pulse duration of the light pulses ranges from 5 microseconds to 1,000 microseconds, and the off time between the light pulses ranges from 10 microseconds to 1 second.

4. The method of claim 3, wherein the light pulses are provided at a duty factor that ranges from 20% to 33% and a pulse repetition rate that ranges from 33 kHz to 40 kHz.

5. The method of claim 1, wherein the light is applied in accordance with an irradiation schedule that includes a plurality of irradiation sessions.

6. The method of claim 5, wherein the irradiation sessions are timed to one or both of (a) a replication cycle of the microorganisms and (b) a depletion and recovery cycle of the photoactive molecules.

7. The method of claim 1, wherein the microorganisms comprise Propionibacterium acnes and the photoactive molecule comprises porphyrin.

8. The method of claim 1, wherein the target comprises one of a region of skin, a tissue or a wound infected by the microorganisms so as to cause a bacterial infection.

9. The method of claim 1, wherein the target comprises an environment contaminated with the microorganisms.

10. The method of claim 1, wherein the target comprises food contaminated with the microorganisms.

11. A method for photoeradication of microorganisms from a target, the method comprising:

irradiating the target with purple or blue light in a pulsed mode of irradiation, wherein the light comprises a plurality of light pulses each of which excites a photoactive molecule capable of photoeradication of the microorganisms and wherein an off time between the light pulses enables return of the photoactive molecule to a ground state to thereby create an oxidation reaction that produces free radicals which destroy a cellular structure of the microorganisms, wherein the light causes photoeradication of all or a portion of the microorganisms.

12. The method of claim 11, wherein the light has a wavelength that ranges from 380 nm to 500 nm.

13. The method of claim 11, wherein the light is applied in accordance with an irradiation schedule that includes a plurality of irradiation sessions.

14. The method of claim 13, wherein the irradiation sessions are timed to one or both of (a) a replication cycle of the microorganisms and (b) a depletion and recovery cycle of the photoactive molecules.

15. The method of claim 11, wherein the microorganisms comprise Propionibacterium acnes and the photoactive molecule comprises porphyrin.

16. The method of claim 11, wherein the target comprises one of a region of skin, a tissue or a wound infected by the microorganisms so as to cause a bacterial infection.

17. The method of claim 11, wherein the target comprises an environment contaminated with the microorganisms.

18. The method of claim 11, wherein the target comprises food contaminated with the microorganisms.

19. A method for photoeradication of microorganisms from a target, the method comprising:

irradiating the target with pulsed purple or blue light in accordance with an irradiation schedule that includes a plurality of irradiation sessions separated by one or more recovery periods, wherein the light applied during each of the irradiation sessions comprises a plurality of light pulses each of which excites a photoactive molecule capable of photoeradication of the microorganisms and wherein an off time between the light pulses enables return of the photoactive molecule to a ground state to thereby create an oxidation reaction that produces free radicals which destroy a cellular structure of the microorganisms, wherein the irradiation sessions are timed to a depletion and recovery cycle of the photoactive molecule in which the irradiation sessions occur during a depletion stage of the cycle and the recovery periods occur during a recovery stage of the cycle, wherein the light causes photoeradication of all or a portion of the microorganisms.

20. The method of claim 19, wherein the irradiation sessions are also timed to a replication cycle of the microorganisms in which the irradiation sessions restart prior to replication of the microorganisms.

21. The method of claim 19, wherein the irradiation schedule results in a survival rate for the microorganisms of less than 50%.

22. The method of claim 19, wherein the irradiation schedule results in a survival rate for the microorganisms of less than 10%.

23. The method of claim 19, wherein the irradiation schedule results in a survival rate for the microorganisms of 0%.

24. The method of claim 19, wherein the light has an average irradiance that ranges from 0.1 mW/cm² to 20 mW/cm² and is provided at a radiant exposure that ranges from 0.5 J/cm² to 60 J/cm² during each of the irradiation sessions.

25. The method of claim 19, wherein the light is provided at a fixed dose during each of the irradiation sessions.

26. The method of claim 19, wherein the light is provided at a dose controlled by feedback from a photo sensor during each of the irradiation sessions, wherein the photo sensor detects light emitted by the photoactive molecule during irradiation of the microorganisms.

27. The method of claim 19, wherein the microorganisms comprise Propionibacterium acnes and the photoactive molecule comprises porphyrin.

28. The method of claim 19, wherein the target comprises one of a region of skin, a tissue or a wound infected by the microorganisms so as to cause a bacterial infection.

29. The method of claim 19, wherein the target comprises an environment contaminated with the microorganisms.

30. The method of claim 19, wherein the target comprises food contaminated with the microorganisms.